diff options
Diffstat (limited to 'src/liblzma/common/stream_decoder_mt.c')
| -rw-r--r-- | src/liblzma/common/stream_decoder_mt.c | 2018 |
1 files changed, 2018 insertions, 0 deletions
diff --git a/src/liblzma/common/stream_decoder_mt.c b/src/liblzma/common/stream_decoder_mt.c new file mode 100644 index 0000000..76212b4 --- /dev/null +++ b/src/liblzma/common/stream_decoder_mt.c @@ -0,0 +1,2018 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file stream_decoder_mt.c +/// \brief Multithreaded .xz Stream decoder +// +// Authors: Sebastian Andrzej Siewior +// Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "common.h" +#include "block_decoder.h" +#include "stream_decoder.h" +#include "index.h" +#include "outqueue.h" + + +typedef enum { + /// Waiting for work. + /// Main thread may change this to THR_RUN or THR_EXIT. + THR_IDLE, + + /// Decoding is in progress. + /// Main thread may change this to THR_STOP or THR_EXIT. + /// The worker thread may change this to THR_IDLE. + THR_RUN, + + /// The main thread wants the thread to stop whatever it was doing + /// but not exit. Main thread may change this to THR_EXIT. + /// The worker thread may change this to THR_IDLE. + THR_STOP, + + /// The main thread wants the thread to exit. + THR_EXIT, + +} worker_state; + + +typedef enum { + /// Partial updates (storing of worker thread progress + /// to lzma_outbuf) are disabled. + PARTIAL_DISABLED, + + /// Main thread requests partial updates to be enabled but + /// no partial update has been done by the worker thread yet. + /// + /// Changing from PARTIAL_DISABLED to PARTIAL_START requires + /// use of the worker-thread mutex. Other transitions don't + /// need a mutex. + PARTIAL_START, + + /// Partial updates are enabled and the worker thread has done + /// at least one partial update. + PARTIAL_ENABLED, + +} partial_update_mode; + + +struct worker_thread { + /// Worker state is protected with our mutex. + worker_state state; + + /// Input buffer that will contain the whole Block except Block Header. + uint8_t *in; + + /// Amount of memory allocated for "in" + size_t in_size; + + /// Number of bytes written to "in" by the main thread + size_t in_filled; + + /// Number of bytes consumed from "in" by the worker thread. + size_t in_pos; + + /// Amount of uncompressed data that has been decoded. This local + /// copy is needed because updating outbuf->pos requires locking + /// the main mutex (coder->mutex). + size_t out_pos; + + /// Pointer to the main structure is needed to (1) lock the main + /// mutex (coder->mutex) when updating outbuf->pos and (2) when + /// putting this thread back to the stack of free threads. + struct lzma_stream_coder *coder; + + /// The allocator is set by the main thread. Since a copy of the + /// pointer is kept here, the application must not change the + /// allocator before calling lzma_end(). + const lzma_allocator *allocator; + + /// Output queue buffer to which the uncompressed data is written. + lzma_outbuf *outbuf; + + /// Amount of compressed data that has already been decompressed. + /// This is updated from in_pos when our mutex is locked. + /// This is size_t, not uint64_t, because per-thread progress + /// is limited to sizes of allocated buffers. + size_t progress_in; + + /// Like progress_in but for uncompressed data. + size_t progress_out; + + /// Updating outbuf->pos requires locking the main mutex + /// (coder->mutex). Since the main thread will only read output + /// from the oldest outbuf in the queue, only the worker thread + /// that is associated with the oldest outbuf needs to update its + /// outbuf->pos. This avoids useless mutex contention that would + /// happen if all worker threads were frequently locking the main + /// mutex to update their outbuf->pos. + /// + /// Only when partial_update is something else than PARTIAL_DISABLED, + /// this worker thread will update outbuf->pos after each call to + /// the Block decoder. + partial_update_mode partial_update; + + /// Block decoder + lzma_next_coder block_decoder; + + /// Thread-specific Block options are needed because the Block + /// decoder modifies the struct given to it at initialization. + lzma_block block_options; + + /// Filter chain memory usage + uint64_t mem_filters; + + /// Next structure in the stack of free worker threads. + struct worker_thread *next; + + mythread_mutex mutex; + mythread_cond cond; + + /// The ID of this thread is used to join the thread + /// when it's not needed anymore. + mythread thread_id; +}; + + +struct lzma_stream_coder { + enum { + SEQ_STREAM_HEADER, + SEQ_BLOCK_HEADER, + SEQ_BLOCK_INIT, + SEQ_BLOCK_THR_INIT, + SEQ_BLOCK_THR_RUN, + SEQ_BLOCK_DIRECT_INIT, + SEQ_BLOCK_DIRECT_RUN, + SEQ_INDEX_WAIT_OUTPUT, + SEQ_INDEX_DECODE, + SEQ_STREAM_FOOTER, + SEQ_STREAM_PADDING, + SEQ_ERROR, + } sequence; + + /// Block decoder + lzma_next_coder block_decoder; + + /// Every Block Header will be decoded into this structure. + /// This is also used to initialize a Block decoder when in + /// direct mode. In threaded mode, a thread-specific copy will + /// be made for decoder initialization because the Block decoder + /// will modify the structure given to it. + lzma_block block_options; + + /// Buffer to hold a filter chain for Block Header decoding and + /// initialization. These are freed after successful Block decoder + /// initialization or at stream_decoder_mt_end(). The thread-specific + /// copy of block_options won't hold a pointer to filters[] after + /// initialization. + lzma_filter filters[LZMA_FILTERS_MAX + 1]; + + /// Stream Flags from Stream Header + lzma_stream_flags stream_flags; + + /// Index is hashed so that it can be compared to the sizes of Blocks + /// with O(1) memory usage. + lzma_index_hash *index_hash; + + + /// Maximum wait time if cannot use all the input and cannot + /// fill the output buffer. This is in milliseconds. + uint32_t timeout; + + + /// Error code from a worker thread. + /// + /// \note Use mutex. + lzma_ret thread_error; + + /// Error code to return after pending output has been copied out. If + /// set in read_output_and_wait(), this is a mirror of thread_error. + /// If set in stream_decode_mt() then it's, for example, error that + /// occurred when decoding Block Header. + lzma_ret pending_error; + + /// Number of threads that will be created at maximum. + uint32_t threads_max; + + /// Number of thread structures that have been initialized from + /// "threads", and thus the number of worker threads actually + /// created so far. + uint32_t threads_initialized; + + /// Array of allocated thread-specific structures. When no threads + /// are in use (direct mode) this is NULL. In threaded mode this + /// points to an array of threads_max number of worker_thread structs. + struct worker_thread *threads; + + /// Stack of free threads. When a thread finishes, it puts itself + /// back into this stack. This starts as empty because threads + /// are created only when actually needed. + /// + /// \note Use mutex. + struct worker_thread *threads_free; + + /// The most recent worker thread to which the main thread writes + /// the new input from the application. + struct worker_thread *thr; + + /// Output buffer queue for decompressed data from the worker threads + /// + /// \note Use mutex with operations that need it. + lzma_outq outq; + + mythread_mutex mutex; + mythread_cond cond; + + + /// Memory usage that will not be exceeded in multi-threaded mode. + /// Single-threaded mode can exceed this even by a large amount. + uint64_t memlimit_threading; + + /// Memory usage limit that should never be exceeded. + /// LZMA_MEMLIMIT_ERROR will be returned if decoding isn't possible + /// even in single-threaded mode without exceeding this limit. + uint64_t memlimit_stop; + + /// Amount of memory in use by the direct mode decoder + /// (coder->block_decoder). In threaded mode this is 0. + uint64_t mem_direct_mode; + + /// Amount of memory needed by the running worker threads. + /// This doesn't include the memory needed by the output buffer. + /// + /// \note Use mutex. + uint64_t mem_in_use; + + /// Amount of memory used by the idle (cached) threads. + /// + /// \note Use mutex. + uint64_t mem_cached; + + + /// Amount of memory needed for the filter chain of the next Block. + uint64_t mem_next_filters; + + /// Amount of memory needed for the thread-specific input buffer + /// for the next Block. + uint64_t mem_next_in; + + /// Amount of memory actually needed to decode the next Block + /// in threaded mode. This is + /// mem_next_filters + mem_next_in + memory needed for lzma_outbuf. + uint64_t mem_next_block; + + + /// Amount of compressed data in Stream Header + Blocks that have + /// already been finished. + /// + /// \note Use mutex. + uint64_t progress_in; + + /// Amount of uncompressed data in Blocks that have already + /// been finished. + /// + /// \note Use mutex. + uint64_t progress_out; + + + /// If true, LZMA_NO_CHECK is returned if the Stream has + /// no integrity check. + bool tell_no_check; + + /// If true, LZMA_UNSUPPORTED_CHECK is returned if the Stream has + /// an integrity check that isn't supported by this liblzma build. + bool tell_unsupported_check; + + /// If true, LZMA_GET_CHECK is returned after decoding Stream Header. + bool tell_any_check; + + /// If true, we will tell the Block decoder to skip calculating + /// and verifying the integrity check. + bool ignore_check; + + /// If true, we will decode concatenated Streams that possibly have + /// Stream Padding between or after them. LZMA_STREAM_END is returned + /// once the application isn't giving us any new input (LZMA_FINISH), + /// and we aren't in the middle of a Stream, and possible + /// Stream Padding is a multiple of four bytes. + bool concatenated; + + /// If true, we will return any errors immediately instead of first + /// producing all output before the location of the error. + bool fail_fast; + + + /// When decoding concatenated Streams, this is true as long as we + /// are decoding the first Stream. This is needed to avoid misleading + /// LZMA_FORMAT_ERROR in case the later Streams don't have valid magic + /// bytes. + bool first_stream; + + /// This is used to track if the previous call to stream_decode_mt() + /// had output space (*out_pos < out_size) and managed to fill the + /// output buffer (*out_pos == out_size). This may be set to true + /// in read_output_and_wait(). This is read and then reset to false + /// at the beginning of stream_decode_mt(). + /// + /// This is needed to support applications that call lzma_code() in + /// such a way that more input is provided only when lzma_code() + /// didn't fill the output buffer completely. Basically, this makes + /// it easier to convert such applications from single-threaded + /// decoder to multi-threaded decoder. + bool out_was_filled; + + /// Write position in buffer[] and position in Stream Padding + size_t pos; + + /// Buffer to hold Stream Header, Block Header, and Stream Footer. + /// Block Header has biggest maximum size. + uint8_t buffer[LZMA_BLOCK_HEADER_SIZE_MAX]; +}; + + +/// Enables updating of outbuf->pos. This is a callback function that is +/// used with lzma_outq_enable_partial_output(). +static void +worker_enable_partial_update(void *thr_ptr) +{ + struct worker_thread *thr = thr_ptr; + + mythread_sync(thr->mutex) { + thr->partial_update = PARTIAL_START; + mythread_cond_signal(&thr->cond); + } +} + + +/// Things do to at THR_STOP or when finishing a Block. +/// This is called with thr->mutex locked. +static void +worker_stop(struct worker_thread *thr) +{ + // Update memory usage counters. + thr->coder->mem_in_use -= thr->in_size; + thr->in_size = 0; // thr->in was freed above. + + thr->coder->mem_in_use -= thr->mem_filters; + thr->coder->mem_cached += thr->mem_filters; + + // Put this thread to the stack of free threads. + thr->next = thr->coder->threads_free; + thr->coder->threads_free = thr; + + mythread_cond_signal(&thr->coder->cond); + return; +} + + +static MYTHREAD_RET_TYPE +worker_decoder(void *thr_ptr) +{ + struct worker_thread *thr = thr_ptr; + size_t in_filled; + partial_update_mode partial_update; + lzma_ret ret; + +next_loop_lock: + + mythread_mutex_lock(&thr->mutex); +next_loop_unlocked: + + if (thr->state == THR_IDLE) { + mythread_cond_wait(&thr->cond, &thr->mutex); + goto next_loop_unlocked; + } + + if (thr->state == THR_EXIT) { + mythread_mutex_unlock(&thr->mutex); + + lzma_free(thr->in, thr->allocator); + lzma_next_end(&thr->block_decoder, thr->allocator); + + mythread_mutex_destroy(&thr->mutex); + mythread_cond_destroy(&thr->cond); + + return MYTHREAD_RET_VALUE; + } + + if (thr->state == THR_STOP) { + thr->state = THR_IDLE; + mythread_mutex_unlock(&thr->mutex); + + mythread_sync(thr->coder->mutex) { + worker_stop(thr); + } + + goto next_loop_lock; + } + + assert(thr->state == THR_RUN); + + // Update progress info for get_progress(). + thr->progress_in = thr->in_pos; + thr->progress_out = thr->out_pos; + + // If we don't have any new input, wait for a signal from the main + // thread except if partial output has just been enabled. In that + // case we will do one normal run so that the partial output info + // gets passed to the main thread. The call to block_decoder.code() + // is useless but harmless as it can occur only once per Block. + in_filled = thr->in_filled; + partial_update = thr->partial_update; + + if (in_filled == thr->in_pos && partial_update != PARTIAL_START) { + mythread_cond_wait(&thr->cond, &thr->mutex); + goto next_loop_unlocked; + } + + mythread_mutex_unlock(&thr->mutex); + + // Pass the input in small chunks to the Block decoder. + // This way we react reasonably fast if we are told to stop/exit, + // and (when partial update is enabled) we tell about our progress + // to the main thread frequently enough. + const size_t chunk_size = 16384; + if ((in_filled - thr->in_pos) > chunk_size) + in_filled = thr->in_pos + chunk_size; + + ret = thr->block_decoder.code( + thr->block_decoder.coder, thr->allocator, + thr->in, &thr->in_pos, in_filled, + thr->outbuf->buf, &thr->out_pos, + thr->outbuf->allocated, LZMA_RUN); + + if (ret == LZMA_OK) { + if (partial_update != PARTIAL_DISABLED) { + // The main thread uses thr->mutex to change from + // PARTIAL_DISABLED to PARTIAL_START. The main thread + // doesn't care about this variable after that so we + // can safely change it here to PARTIAL_ENABLED + // without a mutex. + thr->partial_update = PARTIAL_ENABLED; + + // The main thread is reading decompressed data + // from thr->outbuf. Tell the main thread about + // our progress. + // + // NOTE: It's possible that we consumed input without + // producing any new output so it's possible that + // only in_pos has changed. In case of PARTIAL_START + // it is possible that neither in_pos nor out_pos has + // changed. + mythread_sync(thr->coder->mutex) { + thr->outbuf->pos = thr->out_pos; + thr->outbuf->decoder_in_pos = thr->in_pos; + mythread_cond_signal(&thr->coder->cond); + } + } + + goto next_loop_lock; + } + + // Either we finished successfully (LZMA_STREAM_END) or an error + // occurred. Both cases are handled almost identically. The error + // case requires updating thr->coder->thread_error. + // + // The sizes are in the Block Header and the Block decoder + // checks that they match, thus we know these: + assert(ret != LZMA_STREAM_END || thr->in_pos == thr->in_size); + assert(ret != LZMA_STREAM_END + || thr->out_pos == thr->block_options.uncompressed_size); + + // Free the input buffer. Don't update in_size as we need + // it later to update thr->coder->mem_in_use. + lzma_free(thr->in, thr->allocator); + thr->in = NULL; + + mythread_sync(thr->mutex) { + if (thr->state != THR_EXIT) + thr->state = THR_IDLE; + } + + mythread_sync(thr->coder->mutex) { + // Move our progress info to the main thread. + thr->coder->progress_in += thr->in_pos; + thr->coder->progress_out += thr->out_pos; + thr->progress_in = 0; + thr->progress_out = 0; + + // Mark the outbuf as finished. + thr->outbuf->pos = thr->out_pos; + thr->outbuf->decoder_in_pos = thr->in_pos; + thr->outbuf->finished = true; + thr->outbuf->finish_ret = ret; + thr->outbuf = NULL; + + // If an error occurred, tell it to the main thread. + if (ret != LZMA_STREAM_END + && thr->coder->thread_error == LZMA_OK) + thr->coder->thread_error = ret; + + worker_stop(thr); + } + + goto next_loop_lock; +} + + +/// Tells the worker threads to exit and waits for them to terminate. +static void +threads_end(struct lzma_stream_coder *coder, const lzma_allocator *allocator) +{ + for (uint32_t i = 0; i < coder->threads_initialized; ++i) { + mythread_sync(coder->threads[i].mutex) { + coder->threads[i].state = THR_EXIT; + mythread_cond_signal(&coder->threads[i].cond); + } + } + + for (uint32_t i = 0; i < coder->threads_initialized; ++i) + mythread_join(coder->threads[i].thread_id); + + lzma_free(coder->threads, allocator); + coder->threads_initialized = 0; + coder->threads = NULL; + coder->threads_free = NULL; + + // The threads don't update these when they exit. Do it here. + coder->mem_in_use = 0; + coder->mem_cached = 0; + + return; +} + + +static void +threads_stop(struct lzma_stream_coder *coder) +{ + for (uint32_t i = 0; i < coder->threads_initialized; ++i) { + mythread_sync(coder->threads[i].mutex) { + // The state must be changed conditionally because + // THR_IDLE -> THR_STOP is not a valid state change. + if (coder->threads[i].state != THR_IDLE) { + coder->threads[i].state = THR_STOP; + mythread_cond_signal(&coder->threads[i].cond); + } + } + } + + return; +} + + +/// Initialize a new worker_thread structure and create a new thread. +static lzma_ret +initialize_new_thread(struct lzma_stream_coder *coder, + const lzma_allocator *allocator) +{ + // Allocate the coder->threads array if needed. It's done here instead + // of when initializing the decoder because we don't need this if we + // use the direct mode (we may even free coder->threads in the middle + // of the file if we switch from threaded to direct mode). + if (coder->threads == NULL) { + coder->threads = lzma_alloc( + coder->threads_max * sizeof(struct worker_thread), + allocator); + + if (coder->threads == NULL) + return LZMA_MEM_ERROR; + } + + // Pick a free structure. + assert(coder->threads_initialized < coder->threads_max); + struct worker_thread *thr + = &coder->threads[coder->threads_initialized]; + + if (mythread_mutex_init(&thr->mutex)) + goto error_mutex; + + if (mythread_cond_init(&thr->cond)) + goto error_cond; + + thr->state = THR_IDLE; + thr->in = NULL; + thr->in_size = 0; + thr->allocator = allocator; + thr->coder = coder; + thr->outbuf = NULL; + thr->block_decoder = LZMA_NEXT_CODER_INIT; + thr->mem_filters = 0; + + if (mythread_create(&thr->thread_id, worker_decoder, thr)) + goto error_thread; + + ++coder->threads_initialized; + coder->thr = thr; + + return LZMA_OK; + +error_thread: + mythread_cond_destroy(&thr->cond); + +error_cond: + mythread_mutex_destroy(&thr->mutex); + +error_mutex: + return LZMA_MEM_ERROR; +} + + +static lzma_ret +get_thread(struct lzma_stream_coder *coder, const lzma_allocator *allocator) +{ + // If there is a free structure on the stack, use it. + mythread_sync(coder->mutex) { + if (coder->threads_free != NULL) { + coder->thr = coder->threads_free; + coder->threads_free = coder->threads_free->next; + + // The thread is no longer in the cache so subtract + // it from the cached memory usage. Don't add it + // to mem_in_use though; the caller will handle it + // since it knows how much memory it will actually + // use (the filter chain might change). + coder->mem_cached -= coder->thr->mem_filters; + } + } + + if (coder->thr == NULL) { + assert(coder->threads_initialized < coder->threads_max); + + // Initialize a new thread. + return_if_error(initialize_new_thread(coder, allocator)); + } + + coder->thr->in_filled = 0; + coder->thr->in_pos = 0; + coder->thr->out_pos = 0; + + coder->thr->progress_in = 0; + coder->thr->progress_out = 0; + + coder->thr->partial_update = PARTIAL_DISABLED; + + return LZMA_OK; +} + + +static lzma_ret +read_output_and_wait(struct lzma_stream_coder *coder, + const lzma_allocator *allocator, + uint8_t *restrict out, size_t *restrict out_pos, + size_t out_size, + bool *input_is_possible, + bool waiting_allowed, + mythread_condtime *wait_abs, bool *has_blocked) +{ + lzma_ret ret = LZMA_OK; + + mythread_sync(coder->mutex) { + do { + // Get as much output from the queue as is possible + // without blocking. + const size_t out_start = *out_pos; + do { + ret = lzma_outq_read(&coder->outq, allocator, + out, out_pos, out_size, + NULL, NULL); + + // If a Block was finished, tell the worker + // thread of the next Block (if it is still + // running) to start telling the main thread + // when new output is available. + if (ret == LZMA_STREAM_END) + lzma_outq_enable_partial_output( + &coder->outq, + &worker_enable_partial_update); + + // Loop until a Block wasn't finished. + // It's important to loop around even if + // *out_pos == out_size because there could + // be an empty Block that will return + // LZMA_STREAM_END without needing any + // output space. + } while (ret == LZMA_STREAM_END); + + // Check if lzma_outq_read reported an error from + // the Block decoder. + if (ret != LZMA_OK) + break; + + // If the output buffer is now full but it wasn't full + // when this function was called, set out_was_filled. + // This way the next call to stream_decode_mt() knows + // that some output was produced and no output space + // remained in the previous call to stream_decode_mt(). + if (*out_pos == out_size && *out_pos != out_start) + coder->out_was_filled = true; + + // Check if any thread has indicated an error. + if (coder->thread_error != LZMA_OK) { + // If LZMA_FAIL_FAST was used, report errors + // from worker threads immediately. + if (coder->fail_fast) { + ret = coder->thread_error; + break; + } + + // Otherwise set pending_error. The value we + // set here will not actually get used other + // than working as a flag that an error has + // occurred. This is because in SEQ_ERROR + // all output before the error will be read + // first by calling this function, and once we + // reach the location of the (first) error the + // error code from the above lzma_outq_read() + // will be returned to the application. + // + // Use LZMA_PROG_ERROR since the value should + // never leak to the application. It's + // possible that pending_error has already + // been set but that doesn't matter: if we get + // here, pending_error only works as a flag. + coder->pending_error = LZMA_PROG_ERROR; + } + + // Check if decoding of the next Block can be started. + // The memusage of the active threads must be low + // enough, there must be a free buffer slot in the + // output queue, and there must be a free thread + // (that can be either created or an existing one + // reused). + // + // NOTE: This is checked after reading the output + // above because reading the output can free a slot in + // the output queue and also reduce active memusage. + // + // NOTE: If output queue is empty, then input will + // always be possible. + if (input_is_possible != NULL + && coder->memlimit_threading + - coder->mem_in_use + - coder->outq.mem_in_use + >= coder->mem_next_block + && lzma_outq_has_buf(&coder->outq) + && (coder->threads_initialized + < coder->threads_max + || coder->threads_free + != NULL)) { + *input_is_possible = true; + break; + } + + // If the caller doesn't want us to block, return now. + if (!waiting_allowed) + break; + + // This check is needed only when input_is_possible + // is NULL. We must return if we aren't waiting for + // input to become possible and there is no more + // output coming from the queue. + if (lzma_outq_is_empty(&coder->outq)) { + assert(input_is_possible == NULL); + break; + } + + // If there is more data available from the queue, + // our out buffer must be full and we need to return + // so that the application can provide more output + // space. + // + // NOTE: In general lzma_outq_is_readable() can return + // true also when there are no more bytes available. + // This can happen when a Block has finished without + // providing any new output. We know that this is not + // the case because in the beginning of this loop we + // tried to read as much as possible even when we had + // no output space left and the mutex has been locked + // all the time (so worker threads cannot have changed + // anything). Thus there must be actual pending output + // in the queue. + if (lzma_outq_is_readable(&coder->outq)) { + assert(*out_pos == out_size); + break; + } + + // If the application stops providing more input + // in the middle of a Block, there will eventually + // be one worker thread left that is stuck waiting for + // more input (that might never arrive) and a matching + // outbuf which the worker thread cannot finish due + // to lack of input. We must detect this situation, + // otherwise we would end up waiting indefinitely + // (if no timeout is in use) or keep returning + // LZMA_TIMED_OUT while making no progress. Thus, the + // application would never get LZMA_BUF_ERROR from + // lzma_code() which would tell the application that + // no more progress is possible. No LZMA_BUF_ERROR + // means that, for example, truncated .xz files could + // cause an infinite loop. + // + // A worker thread doing partial updates will + // store not only the output position in outbuf->pos + // but also the matching input position in + // outbuf->decoder_in_pos. Here we check if that + // input position matches the amount of input that + // the worker thread has been given (in_filled). + // If so, we must return and not wait as no more + // output will be coming without first getting more + // input to the worker thread. If the application + // keeps calling lzma_code() without providing more + // input, it will eventually get LZMA_BUF_ERROR. + // + // NOTE: We can read partial_update and in_filled + // without thr->mutex as only the main thread + // modifies these variables. decoder_in_pos requires + // coder->mutex which we are already holding. + if (coder->thr != NULL && coder->thr->partial_update + != PARTIAL_DISABLED) { + // There is exactly one outbuf in the queue. + assert(coder->thr->outbuf == coder->outq.head); + assert(coder->thr->outbuf == coder->outq.tail); + + if (coder->thr->outbuf->decoder_in_pos + == coder->thr->in_filled) + break; + } + + // Wait for input or output to become possible. + if (coder->timeout != 0) { + // See the comment in stream_encoder_mt.c + // about why mythread_condtime_set() is used + // like this. + // + // FIXME? + // In contrast to the encoder, this calls + // _condtime_set while the mutex is locked. + if (!*has_blocked) { + *has_blocked = true; + mythread_condtime_set(wait_abs, + &coder->cond, + coder->timeout); + } + + if (mythread_cond_timedwait(&coder->cond, + &coder->mutex, + wait_abs) != 0) { + ret = LZMA_TIMED_OUT; + break; + } + } else { + mythread_cond_wait(&coder->cond, + &coder->mutex); + } + } while (ret == LZMA_OK); + } + + // If we are returning an error, then the application cannot get + // more output from us and thus keeping the threads running is + // useless and waste of CPU time. + if (ret != LZMA_OK && ret != LZMA_TIMED_OUT) + threads_stop(coder); + + return ret; +} + + +static lzma_ret +decode_block_header(struct lzma_stream_coder *coder, + const lzma_allocator *allocator, const uint8_t *restrict in, + size_t *restrict in_pos, size_t in_size) +{ + if (*in_pos >= in_size) + return LZMA_OK; + + if (coder->pos == 0) { + // Detect if it's Index. + if (in[*in_pos] == INDEX_INDICATOR) + return LZMA_INDEX_DETECTED; + + // Calculate the size of the Block Header. Note that + // Block Header decoder wants to see this byte too + // so don't advance *in_pos. + coder->block_options.header_size + = lzma_block_header_size_decode( + in[*in_pos]); + } + + // Copy the Block Header to the internal buffer. + lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, + coder->block_options.header_size); + + // Return if we didn't get the whole Block Header yet. + if (coder->pos < coder->block_options.header_size) + return LZMA_OK; + + coder->pos = 0; + + // Version 1 is needed to support the .ignore_check option. + coder->block_options.version = 1; + + // Block Header decoder will initialize all members of this array + // so we don't need to do it here. + coder->block_options.filters = coder->filters; + + // Decode the Block Header. + return_if_error(lzma_block_header_decode(&coder->block_options, + allocator, coder->buffer)); + + // If LZMA_IGNORE_CHECK was used, this flag needs to be set. + // It has to be set after lzma_block_header_decode() because + // it always resets this to false. + coder->block_options.ignore_check = coder->ignore_check; + + // coder->block_options is ready now. + return LZMA_STREAM_END; +} + + +/// Get the size of the Compressed Data + Block Padding + Check. +static size_t +comp_blk_size(const struct lzma_stream_coder *coder) +{ + return vli_ceil4(coder->block_options.compressed_size) + + lzma_check_size(coder->stream_flags.check); +} + + +/// Returns true if the size (compressed or uncompressed) is such that +/// threaded decompression cannot be used. Sizes that are too big compared +/// to SIZE_MAX must be rejected to avoid integer overflows and truncations +/// when lzma_vli is assigned to a size_t. +static bool +is_direct_mode_needed(lzma_vli size) +{ + return size == LZMA_VLI_UNKNOWN || size > SIZE_MAX / 3; +} + + +static lzma_ret +stream_decoder_reset(struct lzma_stream_coder *coder, + const lzma_allocator *allocator) +{ + // Initialize the Index hash used to verify the Index. + coder->index_hash = lzma_index_hash_init(coder->index_hash, allocator); + if (coder->index_hash == NULL) + return LZMA_MEM_ERROR; + + // Reset the rest of the variables. + coder->sequence = SEQ_STREAM_HEADER; + coder->pos = 0; + + return LZMA_OK; +} + + +static lzma_ret +stream_decode_mt(void *coder_ptr, const lzma_allocator *allocator, + const uint8_t *restrict in, size_t *restrict in_pos, + size_t in_size, + uint8_t *restrict out, size_t *restrict out_pos, + size_t out_size, lzma_action action) +{ + struct lzma_stream_coder *coder = coder_ptr; + + mythread_condtime wait_abs; + bool has_blocked = false; + + // Determine if in SEQ_BLOCK_HEADER and SEQ_BLOCK_THR_RUN we should + // tell read_output_and_wait() to wait until it can fill the output + // buffer (or a timeout occurs). Two conditions must be met: + // + // (1) If the caller provided no new input. The reason for this + // can be, for example, the end of the file or that there is + // a pause in the input stream and more input is available + // a little later. In this situation we should wait for output + // because otherwise we would end up in a busy-waiting loop where + // we make no progress and the application just calls us again + // without providing any new input. This would then result in + // LZMA_BUF_ERROR even though more output would be available + // once the worker threads decode more data. + // + // (2) Even if (1) is true, we will not wait if the previous call to + // this function managed to produce some output and the output + // buffer became full. This is for compatibility with applications + // that call lzma_code() in such a way that new input is provided + // only when the output buffer didn't become full. Without this + // trick such applications would have bad performance (bad + // parallelization due to decoder not getting input fast enough). + // + // NOTE: Such loops might require that timeout is disabled (0) + // if they assume that output-not-full implies that all input has + // been consumed. If and only if timeout is enabled, we may return + // when output isn't full *and* not all input has been consumed. + // + // However, if LZMA_FINISH is used, the above is ignored and we always + // wait (timeout can still cause us to return) because we know that + // we won't get any more input. This matters if the input file is + // truncated and we are doing single-shot decoding, that is, + // timeout = 0 and LZMA_FINISH is used on the first call to + // lzma_code() and the output buffer is known to be big enough + // to hold all uncompressed data: + // + // - If LZMA_FINISH wasn't handled specially, we could return + // LZMA_OK before providing all output that is possible with the + // truncated input. The rest would be available if lzma_code() was + // called again but then it's not single-shot decoding anymore. + // + // - By handling LZMA_FINISH specially here, the first call will + // produce all the output, matching the behavior of the + // single-threaded decoder. + // + // So it's a very specific corner case but also easy to avoid. Note + // that this special handling of LZMA_FINISH has no effect for + // single-shot decoding when the input file is valid (not truncated); + // premature LZMA_OK wouldn't be possible as long as timeout = 0. + const bool waiting_allowed = action == LZMA_FINISH + || (*in_pos == in_size && !coder->out_was_filled); + coder->out_was_filled = false; + + while (true) + switch (coder->sequence) { + case SEQ_STREAM_HEADER: { + // Copy the Stream Header to the internal buffer. + const size_t in_old = *in_pos; + lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, + LZMA_STREAM_HEADER_SIZE); + coder->progress_in += *in_pos - in_old; + + // Return if we didn't get the whole Stream Header yet. + if (coder->pos < LZMA_STREAM_HEADER_SIZE) + return LZMA_OK; + + coder->pos = 0; + + // Decode the Stream Header. + const lzma_ret ret = lzma_stream_header_decode( + &coder->stream_flags, coder->buffer); + if (ret != LZMA_OK) + return ret == LZMA_FORMAT_ERROR && !coder->first_stream + ? LZMA_DATA_ERROR : ret; + + // If we are decoding concatenated Streams, and the later + // Streams have invalid Header Magic Bytes, we give + // LZMA_DATA_ERROR instead of LZMA_FORMAT_ERROR. + coder->first_stream = false; + + // Copy the type of the Check so that Block Header and Block + // decoders see it. + coder->block_options.check = coder->stream_flags.check; + + // Even if we return LZMA_*_CHECK below, we want + // to continue from Block Header decoding. + coder->sequence = SEQ_BLOCK_HEADER; + + // Detect if there's no integrity check or if it is + // unsupported if those were requested by the application. + if (coder->tell_no_check && coder->stream_flags.check + == LZMA_CHECK_NONE) + return LZMA_NO_CHECK; + + if (coder->tell_unsupported_check + && !lzma_check_is_supported( + coder->stream_flags.check)) + return LZMA_UNSUPPORTED_CHECK; + + if (coder->tell_any_check) + return LZMA_GET_CHECK; + } + + // Fall through + + case SEQ_BLOCK_HEADER: { + const size_t in_old = *in_pos; + const lzma_ret ret = decode_block_header(coder, allocator, + in, in_pos, in_size); + coder->progress_in += *in_pos - in_old; + + if (ret == LZMA_OK) { + // We didn't decode the whole Block Header yet. + // + // Read output from the queue before returning. This + // is important because it is possible that the + // application doesn't have any new input available + // immediately. If we didn't try to copy output from + // the output queue here, lzma_code() could end up + // returning LZMA_BUF_ERROR even though queued output + // is available. + // + // If the lzma_code() call provided at least one input + // byte, only copy as much data from the output queue + // as is available immediately. This way the + // application will be able to provide more input + // without a delay. + // + // On the other hand, if lzma_code() was called with + // an empty input buffer(*), treat it specially: try + // to fill the output buffer even if it requires + // waiting for the worker threads to provide output + // (timeout, if specified, can still cause us to + // return). + // + // - This way the application will be able to get all + // data that can be decoded from the input provided + // so far. + // + // - We avoid both premature LZMA_BUF_ERROR and + // busy-waiting where the application repeatedly + // calls lzma_code() which immediately returns + // LZMA_OK without providing new data. + // + // - If the queue becomes empty, we won't wait + // anything and will return LZMA_OK immediately + // (coder->timeout is completely ignored). + // + // (*) See the comment at the beginning of this + // function how waiting_allowed is determined + // and why there is an exception to the rule + // of "called with an empty input buffer". + assert(*in_pos == in_size); + + // If LZMA_FINISH was used we know that we won't get + // more input, so the file must be truncated if we + // get here. If worker threads don't detect any + // errors, eventually there will be no more output + // while we keep returning LZMA_OK which gets + // converted to LZMA_BUF_ERROR in lzma_code(). + // + // If fail-fast is enabled then we will return + // immediately using LZMA_DATA_ERROR instead of + // LZMA_OK or LZMA_BUF_ERROR. Rationale for the + // error code: + // + // - Worker threads may have a large amount of + // not-yet-decoded input data and we don't + // know for sure if all data is valid. Bad + // data there would result in LZMA_DATA_ERROR + // when fail-fast isn't used. + // + // - Immediate LZMA_BUF_ERROR would be a bit weird + // considering the older liblzma code. lzma_code() + // even has an assertion to prevent coders from + // returning LZMA_BUF_ERROR directly. + // + // The downside of this is that with fail-fast apps + // cannot always distinguish between corrupt and + // truncated files. + if (action == LZMA_FINISH && coder->fail_fast) { + // We won't produce any more output. Stop + // the unfinished worker threads so they + // won't waste CPU time. + threads_stop(coder); + return LZMA_DATA_ERROR; + } + + // read_output_and_wait() will call threads_stop() + // if needed so with that we can use return_if_error. + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + NULL, waiting_allowed, + &wait_abs, &has_blocked)); + + if (coder->pending_error != LZMA_OK) { + coder->sequence = SEQ_ERROR; + break; + } + + return LZMA_OK; + } + + if (ret == LZMA_INDEX_DETECTED) { + coder->sequence = SEQ_INDEX_WAIT_OUTPUT; + break; + } + + // See if an error occurred. + if (ret != LZMA_STREAM_END) { + // NOTE: Here and in all other places where + // pending_error is set, it may overwrite the value + // (LZMA_PROG_ERROR) set by read_output_and_wait(). + // That function might overwrite value set here too. + // These are fine because when read_output_and_wait() + // sets pending_error, it actually works as a flag + // variable only ("some error has occurred") and the + // actual value of pending_error is not used in + // SEQ_ERROR. In such cases SEQ_ERROR will eventually + // get the correct error code from the return value of + // a later read_output_and_wait() call. + coder->pending_error = ret; + coder->sequence = SEQ_ERROR; + break; + } + + // Calculate the memory usage of the filters / Block decoder. + coder->mem_next_filters = lzma_raw_decoder_memusage( + coder->filters); + + if (coder->mem_next_filters == UINT64_MAX) { + // One or more unknown Filter IDs. + coder->pending_error = LZMA_OPTIONS_ERROR; + coder->sequence = SEQ_ERROR; + break; + } + + coder->sequence = SEQ_BLOCK_INIT; + } + + // Fall through + + case SEQ_BLOCK_INIT: { + // Check if decoding is possible at all with the current + // memlimit_stop which we must never exceed. + // + // This needs to be the first thing in SEQ_BLOCK_INIT + // to make it possible to restart decoding after increasing + // memlimit_stop with lzma_memlimit_set(). + if (coder->mem_next_filters > coder->memlimit_stop) { + // Flush pending output before returning + // LZMA_MEMLIMIT_ERROR. If the application doesn't + // want to increase the limit, at least it will get + // all the output possible so far. + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + NULL, true, &wait_abs, &has_blocked)); + + if (!lzma_outq_is_empty(&coder->outq)) + return LZMA_OK; + + return LZMA_MEMLIMIT_ERROR; + } + + // Check if the size information is available in Block Header. + // If it is, check if the sizes are small enough that we don't + // need to worry *too* much about integer overflows later in + // the code. If these conditions are not met, we must use the + // single-threaded direct mode. + if (is_direct_mode_needed(coder->block_options.compressed_size) + || is_direct_mode_needed( + coder->block_options.uncompressed_size)) { + coder->sequence = SEQ_BLOCK_DIRECT_INIT; + break; + } + + // Calculate the amount of memory needed for the input and + // output buffers in threaded mode. + // + // These cannot overflow because we already checked that + // the sizes are small enough using is_direct_mode_needed(). + coder->mem_next_in = comp_blk_size(coder); + const uint64_t mem_buffers = coder->mem_next_in + + lzma_outq_outbuf_memusage( + coder->block_options.uncompressed_size); + + // Add the amount needed by the filters. + // Avoid integer overflows. + if (UINT64_MAX - mem_buffers < coder->mem_next_filters) { + // Use direct mode if the memusage would overflow. + // This is a theoretical case that shouldn't happen + // in practice unless the input file is weird (broken + // or malicious). + coder->sequence = SEQ_BLOCK_DIRECT_INIT; + break; + } + + // Amount of memory needed to decode this Block in + // threaded mode: + coder->mem_next_block = coder->mem_next_filters + mem_buffers; + + // If this alone would exceed memlimit_threading, then we must + // use the single-threaded direct mode. + if (coder->mem_next_block > coder->memlimit_threading) { + coder->sequence = SEQ_BLOCK_DIRECT_INIT; + break; + } + + // Use the threaded mode. Free the direct mode decoder in + // case it has been initialized. + lzma_next_end(&coder->block_decoder, allocator); + coder->mem_direct_mode = 0; + + // Since we already know what the sizes are supposed to be, + // we can already add them to the Index hash. The Block + // decoder will verify the values while decoding. + const lzma_ret ret = lzma_index_hash_append(coder->index_hash, + lzma_block_unpadded_size( + &coder->block_options), + coder->block_options.uncompressed_size); + if (ret != LZMA_OK) { + coder->pending_error = ret; + coder->sequence = SEQ_ERROR; + break; + } + + coder->sequence = SEQ_BLOCK_THR_INIT; + } + + // Fall through + + case SEQ_BLOCK_THR_INIT: { + // We need to wait for a multiple conditions to become true + // until we can initialize the Block decoder and let a worker + // thread decode it: + // + // - Wait for the memory usage of the active threads to drop + // so that starting the decoding of this Block won't make + // us go over memlimit_threading. + // + // - Wait for at least one free output queue slot. + // + // - Wait for a free worker thread. + // + // While we wait, we must copy decompressed data to the out + // buffer and catch possible decoder errors. + // + // read_output_and_wait() does all the above. + bool block_can_start = false; + + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + &block_can_start, true, + &wait_abs, &has_blocked)); + + if (coder->pending_error != LZMA_OK) { + coder->sequence = SEQ_ERROR; + break; + } + + if (!block_can_start) { + // It's not a timeout because return_if_error handles + // it already. Output queue cannot be empty either + // because in that case block_can_start would have + // been true. Thus the output buffer must be full and + // the queue isn't empty. + assert(*out_pos == out_size); + assert(!lzma_outq_is_empty(&coder->outq)); + return LZMA_OK; + } + + // We know that we can start decoding this Block without + // exceeding memlimit_threading. However, to stay below + // memlimit_threading may require freeing some of the + // cached memory. + // + // Get a local copy of variables that require locking the + // mutex. It is fine if the worker threads modify the real + // values after we read these as those changes can only be + // towards more favorable conditions (less memory in use, + // more in cache). + // + // These are initialized to silence warnings. + uint64_t mem_in_use = 0; + uint64_t mem_cached = 0; + struct worker_thread *thr = NULL; + + mythread_sync(coder->mutex) { + mem_in_use = coder->mem_in_use; + mem_cached = coder->mem_cached; + thr = coder->threads_free; + } + + // The maximum amount of memory that can be held by other + // threads and cached buffers while allowing us to start + // decoding the next Block. + const uint64_t mem_max = coder->memlimit_threading + - coder->mem_next_block; + + // If the existing allocations are so large that starting + // to decode this Block might exceed memlimit_threads, + // try to free memory from the output queue cache first. + // + // NOTE: This math assumes the worst case. It's possible + // that the limit wouldn't be exceeded if the existing cached + // allocations are reused. + if (mem_in_use + mem_cached + coder->outq.mem_allocated + > mem_max) { + // Clear the outq cache except leave one buffer in + // the cache if its size is correct. That way we + // don't free and almost immediately reallocate + // an identical buffer. + lzma_outq_clear_cache2(&coder->outq, allocator, + coder->block_options.uncompressed_size); + } + + // If there is at least one worker_thread in the cache and + // the existing allocations are so large that starting to + // decode this Block might exceed memlimit_threads, free + // memory by freeing cached Block decoders. + // + // NOTE: The comparison is different here than above. + // Here we don't care about cached buffers in outq anymore + // and only look at memory actually in use. This is because + // if there is something in outq cache, it's a single buffer + // that can be used as is. We ensured this in the above + // if-block. + uint64_t mem_freed = 0; + if (thr != NULL && mem_in_use + mem_cached + + coder->outq.mem_in_use > mem_max) { + // Don't free the first Block decoder if its memory + // usage isn't greater than what this Block will need. + // Typically the same filter chain is used for all + // Blocks so this way the allocations can be reused + // when get_thread() picks the first worker_thread + // from the cache. + if (thr->mem_filters <= coder->mem_next_filters) + thr = thr->next; + + while (thr != NULL) { + lzma_next_end(&thr->block_decoder, allocator); + mem_freed += thr->mem_filters; + thr->mem_filters = 0; + thr = thr->next; + } + } + + // Update the memory usage counters. Note that coder->mem_* + // may have changed since we read them so we must subtract + // or add the changes. + mythread_sync(coder->mutex) { + coder->mem_cached -= mem_freed; + + // Memory needed for the filters and the input buffer. + // The output queue takes care of its own counter so + // we don't touch it here. + // + // NOTE: After this, coder->mem_in_use + + // coder->mem_cached might count the same thing twice. + // If so, this will get corrected in get_thread() when + // a worker_thread is picked from coder->free_threads + // and its memory usage is subtracted from mem_cached. + coder->mem_in_use += coder->mem_next_in + + coder->mem_next_filters; + } + + // Allocate memory for the output buffer in the output queue. + lzma_ret ret = lzma_outq_prealloc_buf( + &coder->outq, allocator, + coder->block_options.uncompressed_size); + if (ret != LZMA_OK) { + threads_stop(coder); + return ret; + } + + // Set up coder->thr. + ret = get_thread(coder, allocator); + if (ret != LZMA_OK) { + threads_stop(coder); + return ret; + } + + // The new Block decoder memory usage is already counted in + // coder->mem_in_use. Store it in the thread too. + coder->thr->mem_filters = coder->mem_next_filters; + + // Initialize the Block decoder. + coder->thr->block_options = coder->block_options; + ret = lzma_block_decoder_init( + &coder->thr->block_decoder, allocator, + &coder->thr->block_options); + + // Free the allocated filter options since they are needed + // only to initialize the Block decoder. + lzma_filters_free(coder->filters, allocator); + coder->thr->block_options.filters = NULL; + + // Check if memory usage calculation and Block encoder + // initialization succeeded. + if (ret != LZMA_OK) { + coder->pending_error = ret; + coder->sequence = SEQ_ERROR; + break; + } + + // Allocate the input buffer. + coder->thr->in_size = coder->mem_next_in; + coder->thr->in = lzma_alloc(coder->thr->in_size, allocator); + if (coder->thr->in == NULL) { + threads_stop(coder); + return LZMA_MEM_ERROR; + } + + // Get the preallocated output buffer. + coder->thr->outbuf = lzma_outq_get_buf( + &coder->outq, coder->thr); + + // Start the decoder. + mythread_sync(coder->thr->mutex) { + assert(coder->thr->state == THR_IDLE); + coder->thr->state = THR_RUN; + mythread_cond_signal(&coder->thr->cond); + } + + // Enable output from the thread that holds the oldest output + // buffer in the output queue (if such a thread exists). + mythread_sync(coder->mutex) { + lzma_outq_enable_partial_output(&coder->outq, + &worker_enable_partial_update); + } + + coder->sequence = SEQ_BLOCK_THR_RUN; + } + + // Fall through + + case SEQ_BLOCK_THR_RUN: { + if (action == LZMA_FINISH && coder->fail_fast) { + // We know that we won't get more input and that + // the caller wants fail-fast behavior. If we see + // that we don't have enough input to finish this + // Block, return LZMA_DATA_ERROR immediately. + // See SEQ_BLOCK_HEADER for the error code rationale. + const size_t in_avail = in_size - *in_pos; + const size_t in_needed = coder->thr->in_size + - coder->thr->in_filled; + if (in_avail < in_needed) { + threads_stop(coder); + return LZMA_DATA_ERROR; + } + } + + // Copy input to the worker thread. + size_t cur_in_filled = coder->thr->in_filled; + lzma_bufcpy(in, in_pos, in_size, coder->thr->in, + &cur_in_filled, coder->thr->in_size); + + // Tell the thread how much we copied. + mythread_sync(coder->thr->mutex) { + coder->thr->in_filled = cur_in_filled; + + // NOTE: Most of the time we are copying input faster + // than the thread can decode so most of the time + // calling mythread_cond_signal() is useless but + // we cannot make it conditional because thr->in_pos + // is updated without a mutex. And the overhead should + // be very much negligible anyway. + mythread_cond_signal(&coder->thr->cond); + } + + // Read output from the output queue. Just like in + // SEQ_BLOCK_HEADER, we wait to fill the output buffer + // only if waiting_allowed was set to true in the beginning + // of this function (see the comment there). + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + NULL, waiting_allowed, + &wait_abs, &has_blocked)); + + if (coder->pending_error != LZMA_OK) { + coder->sequence = SEQ_ERROR; + break; + } + + // Return if the input didn't contain the whole Block. + if (coder->thr->in_filled < coder->thr->in_size) { + assert(*in_pos == in_size); + return LZMA_OK; + } + + // The whole Block has been copied to the thread-specific + // buffer. Continue from the next Block Header or Index. + coder->thr = NULL; + coder->sequence = SEQ_BLOCK_HEADER; + break; + } + + case SEQ_BLOCK_DIRECT_INIT: { + // Wait for the threads to finish and that all decoded data + // has been copied to the output. That is, wait until the + // output queue becomes empty. + // + // NOTE: No need to check for coder->pending_error as + // we aren't consuming any input until the queue is empty + // and if there is a pending error, read_output_and_wait() + // will eventually return it before the queue is empty. + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + NULL, true, &wait_abs, &has_blocked)); + if (!lzma_outq_is_empty(&coder->outq)) + return LZMA_OK; + + // Free the cached output buffers. + lzma_outq_clear_cache(&coder->outq, allocator); + + // Get rid of the worker threads, including the coder->threads + // array. + threads_end(coder, allocator); + + // Initialize the Block decoder. + const lzma_ret ret = lzma_block_decoder_init( + &coder->block_decoder, allocator, + &coder->block_options); + + // Free the allocated filter options since they are needed + // only to initialize the Block decoder. + lzma_filters_free(coder->filters, allocator); + coder->block_options.filters = NULL; + + // Check if Block decoder initialization succeeded. + if (ret != LZMA_OK) + return ret; + + // Make the memory usage visible to _memconfig(). + coder->mem_direct_mode = coder->mem_next_filters; + + coder->sequence = SEQ_BLOCK_DIRECT_RUN; + } + + // Fall through + + case SEQ_BLOCK_DIRECT_RUN: { + const size_t in_old = *in_pos; + const size_t out_old = *out_pos; + const lzma_ret ret = coder->block_decoder.code( + coder->block_decoder.coder, allocator, + in, in_pos, in_size, out, out_pos, out_size, + action); + coder->progress_in += *in_pos - in_old; + coder->progress_out += *out_pos - out_old; + + if (ret != LZMA_STREAM_END) + return ret; + + // Block decoded successfully. Add the new size pair to + // the Index hash. + return_if_error(lzma_index_hash_append(coder->index_hash, + lzma_block_unpadded_size( + &coder->block_options), + coder->block_options.uncompressed_size)); + + coder->sequence = SEQ_BLOCK_HEADER; + break; + } + + case SEQ_INDEX_WAIT_OUTPUT: + // Flush the output from all worker threads so that we can + // decode the Index without thinking about threading. + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + NULL, true, &wait_abs, &has_blocked)); + + if (!lzma_outq_is_empty(&coder->outq)) + return LZMA_OK; + + coder->sequence = SEQ_INDEX_DECODE; + + // Fall through + + case SEQ_INDEX_DECODE: { + // If we don't have any input, don't call + // lzma_index_hash_decode() since it would return + // LZMA_BUF_ERROR, which we must not do here. + if (*in_pos >= in_size) + return LZMA_OK; + + // Decode the Index and compare it to the hash calculated + // from the sizes of the Blocks (if any). + const size_t in_old = *in_pos; + const lzma_ret ret = lzma_index_hash_decode(coder->index_hash, + in, in_pos, in_size); + coder->progress_in += *in_pos - in_old; + if (ret != LZMA_STREAM_END) + return ret; + + coder->sequence = SEQ_STREAM_FOOTER; + } + + // Fall through + + case SEQ_STREAM_FOOTER: { + // Copy the Stream Footer to the internal buffer. + const size_t in_old = *in_pos; + lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, + LZMA_STREAM_HEADER_SIZE); + coder->progress_in += *in_pos - in_old; + + // Return if we didn't get the whole Stream Footer yet. + if (coder->pos < LZMA_STREAM_HEADER_SIZE) + return LZMA_OK; + + coder->pos = 0; + + // Decode the Stream Footer. The decoder gives + // LZMA_FORMAT_ERROR if the magic bytes don't match, + // so convert that return code to LZMA_DATA_ERROR. + lzma_stream_flags footer_flags; + const lzma_ret ret = lzma_stream_footer_decode( + &footer_flags, coder->buffer); + if (ret != LZMA_OK) + return ret == LZMA_FORMAT_ERROR + ? LZMA_DATA_ERROR : ret; + + // Check that Index Size stored in the Stream Footer matches + // the real size of the Index field. + if (lzma_index_hash_size(coder->index_hash) + != footer_flags.backward_size) + return LZMA_DATA_ERROR; + + // Compare that the Stream Flags fields are identical in + // both Stream Header and Stream Footer. + return_if_error(lzma_stream_flags_compare( + &coder->stream_flags, &footer_flags)); + + if (!coder->concatenated) + return LZMA_STREAM_END; + + coder->sequence = SEQ_STREAM_PADDING; + } + + // Fall through + + case SEQ_STREAM_PADDING: + assert(coder->concatenated); + + // Skip over possible Stream Padding. + while (true) { + if (*in_pos >= in_size) { + // Unless LZMA_FINISH was used, we cannot + // know if there's more input coming later. + if (action != LZMA_FINISH) + return LZMA_OK; + + // Stream Padding must be a multiple of + // four bytes. + return coder->pos == 0 + ? LZMA_STREAM_END + : LZMA_DATA_ERROR; + } + + // If the byte is not zero, it probably indicates + // beginning of a new Stream (or the file is corrupt). + if (in[*in_pos] != 0x00) + break; + + ++*in_pos; + ++coder->progress_in; + coder->pos = (coder->pos + 1) & 3; + } + + // Stream Padding must be a multiple of four bytes (empty + // Stream Padding is OK). + if (coder->pos != 0) { + ++*in_pos; + ++coder->progress_in; + return LZMA_DATA_ERROR; + } + + // Prepare to decode the next Stream. + return_if_error(stream_decoder_reset(coder, allocator)); + break; + + case SEQ_ERROR: + if (!coder->fail_fast) { + // Let the application get all data before the point + // where the error was detected. This matches the + // behavior of single-threaded use. + // + // FIXME? Some errors (LZMA_MEM_ERROR) don't get here, + // they are returned immediately. Thus in rare cases + // the output will be less than in the single-threaded + // mode. Maybe this doesn't matter much in practice. + return_if_error(read_output_and_wait(coder, allocator, + out, out_pos, out_size, + NULL, true, &wait_abs, &has_blocked)); + + // We get here only if the error happened in the main + // thread, for example, unsupported Block Header. + if (!lzma_outq_is_empty(&coder->outq)) + return LZMA_OK; + } + + // We only get here if no errors were detected by the worker + // threads. Errors from worker threads would have already been + // returned by the call to read_output_and_wait() above. + return coder->pending_error; + + default: + assert(0); + return LZMA_PROG_ERROR; + } + + // Never reached +} + + +static void +stream_decoder_mt_end(void *coder_ptr, const lzma_allocator *allocator) +{ + struct lzma_stream_coder *coder = coder_ptr; + + threads_end(coder, allocator); + lzma_outq_end(&coder->outq, allocator); + + lzma_next_end(&coder->block_decoder, allocator); + lzma_filters_free(coder->filters, allocator); + lzma_index_hash_end(coder->index_hash, allocator); + + lzma_free(coder, allocator); + return; +} + + +static lzma_check +stream_decoder_mt_get_check(const void *coder_ptr) +{ + const struct lzma_stream_coder *coder = coder_ptr; + return coder->stream_flags.check; +} + + +static lzma_ret +stream_decoder_mt_memconfig(void *coder_ptr, uint64_t *memusage, + uint64_t *old_memlimit, uint64_t new_memlimit) +{ + // NOTE: This function gets/sets memlimit_stop. For now, + // memlimit_threading cannot be modified after initialization. + // + // *memusage will include cached memory too. Excluding cached memory + // would be misleading and it wouldn't help the applications to + // know how much memory is actually needed to decompress the file + // because the higher the number of threads and the memlimits are + // the more memory the decoder may use. + // + // Setting a new limit includes the cached memory too and too low + // limits will be rejected. Alternative could be to free the cached + // memory immediately if that helps to bring the limit down but + // the current way is the simplest. It's unlikely that limit needs + // to be lowered in the middle of a file anyway; the typical reason + // to want a new limit is to increase after LZMA_MEMLIMIT_ERROR + // and even such use isn't common. + struct lzma_stream_coder *coder = coder_ptr; + + mythread_sync(coder->mutex) { + *memusage = coder->mem_direct_mode + + coder->mem_in_use + + coder->mem_cached + + coder->outq.mem_allocated; + } + + // If no filter chains are allocated, *memusage may be zero. + // Always return at least LZMA_MEMUSAGE_BASE. + if (*memusage < LZMA_MEMUSAGE_BASE) + *memusage = LZMA_MEMUSAGE_BASE; + + *old_memlimit = coder->memlimit_stop; + + if (new_memlimit != 0) { + if (new_memlimit < *memusage) + return LZMA_MEMLIMIT_ERROR; + + coder->memlimit_stop = new_memlimit; + } + + return LZMA_OK; +} + + +static void +stream_decoder_mt_get_progress(void *coder_ptr, + uint64_t *progress_in, uint64_t *progress_out) +{ + struct lzma_stream_coder *coder = coder_ptr; + + // Lock coder->mutex to prevent finishing threads from moving their + // progress info from the worker_thread structure to lzma_stream_coder. + mythread_sync(coder->mutex) { + *progress_in = coder->progress_in; + *progress_out = coder->progress_out; + + for (size_t i = 0; i < coder->threads_initialized; ++i) { + mythread_sync(coder->threads[i].mutex) { + *progress_in += coder->threads[i].progress_in; + *progress_out += coder->threads[i] + .progress_out; + } + } + } + + return; +} + + +static lzma_ret +stream_decoder_mt_init(lzma_next_coder *next, const lzma_allocator *allocator, + const lzma_mt *options) +{ + struct lzma_stream_coder *coder; + + if (options->threads == 0 || options->threads > LZMA_THREADS_MAX) + return LZMA_OPTIONS_ERROR; + + if (options->flags & ~LZMA_SUPPORTED_FLAGS) + return LZMA_OPTIONS_ERROR; + + lzma_next_coder_init(&stream_decoder_mt_init, next, allocator); + + coder = next->coder; + if (!coder) { + coder = lzma_alloc(sizeof(struct lzma_stream_coder), allocator); + if (coder == NULL) + return LZMA_MEM_ERROR; + + next->coder = coder; + + if (mythread_mutex_init(&coder->mutex)) { + lzma_free(coder, allocator); + return LZMA_MEM_ERROR; + } + + if (mythread_cond_init(&coder->cond)) { + mythread_mutex_destroy(&coder->mutex); + lzma_free(coder, allocator); + return LZMA_MEM_ERROR; + } + + next->code = &stream_decode_mt; + next->end = &stream_decoder_mt_end; + next->get_check = &stream_decoder_mt_get_check; + next->memconfig = &stream_decoder_mt_memconfig; + next->get_progress = &stream_decoder_mt_get_progress; + + coder->filters[0].id = LZMA_VLI_UNKNOWN; + memzero(&coder->outq, sizeof(coder->outq)); + + coder->block_decoder = LZMA_NEXT_CODER_INIT; + coder->mem_direct_mode = 0; + + coder->index_hash = NULL; + coder->threads = NULL; + coder->threads_free = NULL; + coder->threads_initialized = 0; + } + + // Cleanup old filter chain if one remains after unfinished decoding + // of a previous Stream. + lzma_filters_free(coder->filters, allocator); + + // By allocating threads from scratch we can start memory-usage + // accounting from scratch, too. Changes in filter and block sizes may + // affect number of threads. + // + // FIXME? Reusing should be easy but unlike the single-threaded + // decoder, with some types of input file combinations reusing + // could leave quite a lot of memory allocated but unused (first + // file could allocate a lot, the next files could use fewer + // threads and some of the allocations from the first file would not + // get freed unless memlimit_threading forces us to clear caches). + // + // NOTE: The direct mode decoder isn't freed here if one exists. + // It will be reused or freed as needed in the main loop. + threads_end(coder, allocator); + + // All memusage counters start at 0 (including mem_direct_mode). + // The little extra that is needed for the structs in this file + // get accounted well enough by the filter chain memory usage + // which adds LZMA_MEMUSAGE_BASE for each chain. However, + // stream_decoder_mt_memconfig() has to handle this specially so that + // it will never return less than LZMA_MEMUSAGE_BASE as memory usage. + coder->mem_in_use = 0; + coder->mem_cached = 0; + coder->mem_next_block = 0; + + coder->progress_in = 0; + coder->progress_out = 0; + + coder->sequence = SEQ_STREAM_HEADER; + coder->thread_error = LZMA_OK; + coder->pending_error = LZMA_OK; + coder->thr = NULL; + + coder->timeout = options->timeout; + + coder->memlimit_threading = my_max(1, options->memlimit_threading); + coder->memlimit_stop = my_max(1, options->memlimit_stop); + if (coder->memlimit_threading > coder->memlimit_stop) + coder->memlimit_threading = coder->memlimit_stop; + + coder->tell_no_check = (options->flags & LZMA_TELL_NO_CHECK) != 0; + coder->tell_unsupported_check + = (options->flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0; + coder->tell_any_check = (options->flags & LZMA_TELL_ANY_CHECK) != 0; + coder->ignore_check = (options->flags & LZMA_IGNORE_CHECK) != 0; + coder->concatenated = (options->flags & LZMA_CONCATENATED) != 0; + coder->fail_fast = (options->flags & LZMA_FAIL_FAST) != 0; + + coder->first_stream = true; + coder->out_was_filled = false; + coder->pos = 0; + + coder->threads_max = options->threads; + + return_if_error(lzma_outq_init(&coder->outq, allocator, + coder->threads_max)); + + return stream_decoder_reset(coder, allocator); +} + + +extern LZMA_API(lzma_ret) +lzma_stream_decoder_mt(lzma_stream *strm, const lzma_mt *options) +{ + lzma_next_strm_init(stream_decoder_mt_init, strm, options); + + strm->internal->supported_actions[LZMA_RUN] = true; + strm->internal->supported_actions[LZMA_FINISH] = true; + + return LZMA_OK; +} |