summaryrefslogtreecommitdiffstats
path: root/mozglue/baseprofiler/public/ProfileChunkedBuffer.h
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--mozglue/baseprofiler/public/ProfileChunkedBuffer.h1560
1 files changed, 1560 insertions, 0 deletions
diff --git a/mozglue/baseprofiler/public/ProfileChunkedBuffer.h b/mozglue/baseprofiler/public/ProfileChunkedBuffer.h
new file mode 100644
index 0000000000..ded7fbd08b
--- /dev/null
+++ b/mozglue/baseprofiler/public/ProfileChunkedBuffer.h
@@ -0,0 +1,1560 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef ProfileChunkedBuffer_h
+#define ProfileChunkedBuffer_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/BaseProfilerDetail.h"
+#include "mozilla/NotNull.h"
+#include "mozilla/ProfileBufferChunkManager.h"
+#include "mozilla/ProfileBufferChunkManagerSingle.h"
+#include "mozilla/ProfileBufferEntrySerialization.h"
+#include "mozilla/ProfileChunkedBufferDetail.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/Unused.h"
+
+#include <utility>
+
+#ifdef DEBUG
+# include <cstdio>
+#endif
+
+namespace mozilla {
+
+// Thread-safe buffer that can store blocks of different sizes during defined
+// sessions, using Chunks (from a ChunkManager) as storage.
+//
+// Each *block* contains an *entry* and the entry size:
+// [ entry_size | entry ] [ entry_size | entry ] ...
+//
+// *In-session* is a period of time during which `ProfileChunkedBuffer` allows
+// reading and writing.
+// *Out-of-session*, the `ProfileChunkedBuffer` object is still valid, but
+// contains no data, and gracefully denies accesses.
+//
+// To write an entry, the buffer reserves a block of sufficient size (to contain
+// user data of predetermined size), writes the entry size, and lets the caller
+// fill the entry contents using a ProfileBufferEntryWriter. E.g.:
+// ```
+// ProfileChunkedBuffer cb(...);
+// cb.ReserveAndPut([]() { return sizeof(123); },
+// [&](Maybe<ProfileBufferEntryWriter>& aEW) {
+// if (aEW) { aEW->WriteObject(123); }
+// });
+// ```
+// Other `Put...` functions may be used as shortcuts for simple entries.
+// The objects given to the caller's callbacks should only be used inside the
+// callbacks and not stored elsewhere, because they keep their own references to
+// chunk memory and therefore should not live longer.
+// Different type of objects may be serialized into an entry, see
+// `ProfileBufferEntryWriter::Serializer` for more information.
+//
+// When reading data, the buffer iterates over blocks (it knows how to read the
+// entry size, and therefore move to the next block), and lets the caller read
+// the entry inside of each block. E.g.:
+// ```
+// cb.ReadEach([](ProfileBufferEntryReader& aER) {
+// /* Use ProfileBufferEntryReader functions to read serialized objects. */
+// int n = aER.ReadObject<int>();
+// });
+// ```
+// Different type of objects may be deserialized from an entry, see
+// `ProfileBufferEntryReader::Deserializer` for more information.
+//
+// Writers may retrieve the block index corresponding to an entry
+// (`ProfileBufferBlockIndex` is an opaque type preventing the user from easily
+// modifying it). That index may later be used with `ReadAt` to get back to the
+// entry in that particular block -- if it still exists.
+class ProfileChunkedBuffer {
+ public:
+ using Byte = ProfileBufferChunk::Byte;
+ using Length = ProfileBufferChunk::Length;
+
+ enum class ThreadSafety { WithoutMutex, WithMutex };
+
+ // Default constructor starts out-of-session (nothing to read or write).
+ explicit ProfileChunkedBuffer(ThreadSafety aThreadSafety)
+ : mMutex(aThreadSafety != ThreadSafety::WithoutMutex) {}
+
+ // Start in-session with external chunk manager.
+ ProfileChunkedBuffer(ThreadSafety aThreadSafety,
+ ProfileBufferChunkManager& aChunkManager)
+ : mMutex(aThreadSafety != ThreadSafety::WithoutMutex) {
+ SetChunkManager(aChunkManager);
+ }
+
+ // Start in-session with owned chunk manager.
+ ProfileChunkedBuffer(ThreadSafety aThreadSafety,
+ UniquePtr<ProfileBufferChunkManager>&& aChunkManager)
+ : mMutex(aThreadSafety != ThreadSafety::WithoutMutex) {
+ SetChunkManager(std::move(aChunkManager));
+ }
+
+ ~ProfileChunkedBuffer() {
+ // Do proper clean-up by resetting the chunk manager.
+ ResetChunkManager();
+ }
+
+ // This cannot change during the lifetime of this buffer, so there's no need
+ // to lock.
+ [[nodiscard]] bool IsThreadSafe() const { return mMutex.IsActivated(); }
+
+ [[nodiscard]] bool IsInSession() const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return !!mChunkManager;
+ }
+
+ // Stop using the current chunk manager.
+ // If we own the current chunk manager, it will be destroyed.
+ // This will always clear currently-held chunks, if any.
+ void ResetChunkManager() {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ Unused << ResetChunkManager(lock);
+ }
+
+ // Set the current chunk manager.
+ // The caller is responsible for keeping the chunk manager alive as along as
+ // it's used here (until the next (Re)SetChunkManager, or
+ // ~ProfileChunkedBuffer).
+ void SetChunkManager(ProfileBufferChunkManager& aChunkManager) {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ Unused << ResetChunkManager(lock);
+ SetChunkManager(aChunkManager, lock);
+ }
+
+ // Set the current chunk manager, and keep ownership of it.
+ void SetChunkManager(UniquePtr<ProfileBufferChunkManager>&& aChunkManager) {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ Unused << ResetChunkManager(lock);
+ mOwnedChunkManager = std::move(aChunkManager);
+ if (mOwnedChunkManager) {
+ SetChunkManager(*mOwnedChunkManager, lock);
+ }
+ }
+
+ // Set the current chunk manager, except if it's already the one provided.
+ // The caller is responsible for keeping the chunk manager alive as along as
+ // it's used here (until the next (Re)SetChunkManager, or
+ // ~ProfileChunkedBuffer).
+ void SetChunkManagerIfDifferent(ProfileBufferChunkManager& aChunkManager) {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (!mChunkManager || mChunkManager != &aChunkManager) {
+ Unused << ResetChunkManager(lock);
+ SetChunkManager(aChunkManager, lock);
+ }
+ }
+
+ // Clear the contents of this buffer, ready to receive new chunks.
+ // Note that memory is not freed: No chunks are destroyed, they are all
+ // receycled.
+ // Also the range doesn't reset, instead it continues at some point after the
+ // previous range. This may be useful if the caller may be keeping indexes
+ // into old chunks that have now been cleared, using these indexes will fail
+ // gracefully (instead of potentially pointing into new data).
+ void Clear() {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return;
+ }
+
+ mRangeStart = mRangeEnd = mNextChunkRangeStart;
+ mPushedBlockCount = 0;
+ mClearedBlockCount = 0;
+ mFailedPutBytes = 0;
+
+ // Recycle all released chunks as "next" chunks. This will reduce the number
+ // of future allocations. Also, when using ProfileBufferChunkManagerSingle,
+ // this retrieves the one chunk if it was released.
+ UniquePtr<ProfileBufferChunk> releasedChunks =
+ mChunkManager->GetExtantReleasedChunks();
+ if (releasedChunks) {
+ // Released chunks should be in the "Done" state, they need to be marked
+ // "recycled" before they can be reused.
+ for (ProfileBufferChunk* chunk = releasedChunks.get(); chunk;
+ chunk = chunk->GetNext()) {
+ chunk->MarkRecycled();
+ }
+ mNextChunks = ProfileBufferChunk::Join(std::move(mNextChunks),
+ std::move(releasedChunks));
+ }
+
+ if (mCurrentChunk) {
+ // We already have a current chunk (empty or in-use), mark it "done" and
+ // then "recycled", ready to be reused.
+ mCurrentChunk->MarkDone();
+ mCurrentChunk->MarkRecycled();
+ } else {
+ if (!mNextChunks) {
+ // No current chunk, and no next chunks to recycle, nothing more to do.
+ // The next "Put" operation will try to allocate a chunk as needed.
+ return;
+ }
+
+ // No current chunk, take a next chunk.
+ mCurrentChunk = std::exchange(mNextChunks, mNextChunks->ReleaseNext());
+ }
+
+ // Here, there was already a current chunk, or one has just been taken.
+ // Make sure it's ready to receive new entries.
+ InitializeCurrentChunk(lock);
+ }
+
+ // Buffer maximum length in bytes.
+ Maybe<size_t> BufferLength() const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (!mChunkManager) {
+ return Nothing{};
+ }
+ return Some(mChunkManager->MaxTotalSize());
+ }
+
+ [[nodiscard]] size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return SizeOfExcludingThis(aMallocSizeOf, lock);
+ }
+
+ [[nodiscard]] size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf, lock);
+ }
+
+ // Snapshot of the buffer state.
+ struct State {
+ // Index to/before the first block.
+ ProfileBufferIndex mRangeStart = 1;
+
+ // Index past the last block. Equals mRangeStart if empty.
+ ProfileBufferIndex mRangeEnd = 1;
+
+ // Number of blocks that have been pushed into this buffer.
+ uint64_t mPushedBlockCount = 0;
+
+ // Number of blocks that have been removed from this buffer.
+ // Note: Live entries = pushed - cleared.
+ uint64_t mClearedBlockCount = 0;
+
+ // Number of bytes that could not be put into this buffer.
+ uint64_t mFailedPutBytes = 0;
+ };
+
+ // Get a snapshot of the current state.
+ // When out-of-session, mFirstReadIndex==mNextWriteIndex, and
+ // mPushedBlockCount==mClearedBlockCount==0.
+ // Note that these may change right after this thread-safe call, so they
+ // should only be used for statistical purposes.
+ [[nodiscard]] State GetState() const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return {mRangeStart, mRangeEnd, mPushedBlockCount, mClearedBlockCount,
+ mFailedPutBytes};
+ }
+
+ // In in-session, return the start TimeStamp of the earliest chunk.
+ // If out-of-session, return a null TimeStamp.
+ [[nodiscard]] TimeStamp GetEarliestChunkStartTimeStamp() const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return {};
+ }
+ return mChunkManager->PeekExtantReleasedChunks(
+ [&](const ProfileBufferChunk* aOldestChunk) -> TimeStamp {
+ if (aOldestChunk) {
+ return aOldestChunk->ChunkHeader().mStartTimeStamp;
+ }
+ if (mCurrentChunk) {
+ return mCurrentChunk->ChunkHeader().mStartTimeStamp;
+ }
+ return {};
+ });
+ }
+
+ [[nodiscard]] bool IsEmpty() const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return mRangeStart == mRangeEnd;
+ }
+
+ // True if this buffer is already locked on this thread.
+ // This should be used if some functions may call an already-locked buffer,
+ // e.g.: Put -> memory hook -> profiler_add_native_allocation_marker -> Put.
+ [[nodiscard]] bool IsThreadSafeAndLockedOnCurrentThread() const {
+ return mMutex.IsActivatedAndLockedOnCurrentThread();
+ }
+
+ // Lock the buffer mutex and run the provided callback.
+ // This can be useful when the caller needs to explicitly lock down this
+ // buffer, but not do anything else with it.
+ template <typename Callback>
+ auto LockAndRun(Callback&& aCallback) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return std::forward<Callback>(aCallback)();
+ }
+
+ // Reserve a block that can hold an entry of the given `aCallbackEntryBytes()`
+ // size, write the entry size (ULEB128-encoded), and invoke and return
+ // `aCallback(Maybe<ProfileBufferEntryWriter>&)`.
+ // Note: `aCallbackEntryBytes` is a callback instead of a simple value, to
+ // delay this potentially-expensive computation until after we're checked that
+ // we're in-session; use `Put(Length, Callback)` below if you know the size
+ // already.
+ template <typename CallbackEntryBytes, typename Callback>
+ auto ReserveAndPut(CallbackEntryBytes&& aCallbackEntryBytes,
+ Callback&& aCallback)
+ -> decltype(std::forward<Callback>(aCallback)(
+ std::declval<Maybe<ProfileBufferEntryWriter>&>())) {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+
+ // This can only be read in the 2nd lambda below after it has been written
+ // by the first lambda.
+ Length entryBytes;
+
+ return ReserveAndPutRaw(
+ [&]() {
+ entryBytes = std::forward<CallbackEntryBytes>(aCallbackEntryBytes)();
+ MOZ_ASSERT(entryBytes != 0, "Empty entries are not allowed");
+ return ULEB128Size(entryBytes) + entryBytes;
+ },
+ [&](Maybe<ProfileBufferEntryWriter>& aMaybeEntryWriter) {
+ if (aMaybeEntryWriter.isSome()) {
+ aMaybeEntryWriter->WriteULEB128(entryBytes);
+ MOZ_ASSERT(aMaybeEntryWriter->RemainingBytes() == entryBytes);
+ }
+ return std::forward<Callback>(aCallback)(aMaybeEntryWriter);
+ },
+ lock);
+ }
+
+ template <typename Callback>
+ auto Put(Length aEntryBytes, Callback&& aCallback) {
+ return ReserveAndPut([aEntryBytes]() { return aEntryBytes; },
+ std::forward<Callback>(aCallback));
+ }
+
+ // Add a new entry copied from the given buffer, return block index.
+ ProfileBufferBlockIndex PutFrom(const void* aSrc, Length aBytes) {
+ return ReserveAndPut(
+ [aBytes]() { return aBytes; },
+ [aSrc, aBytes](Maybe<ProfileBufferEntryWriter>& aMaybeEntryWriter) {
+ if (aMaybeEntryWriter.isNothing()) {
+ return ProfileBufferBlockIndex{};
+ }
+ aMaybeEntryWriter->WriteBytes(aSrc, aBytes);
+ return aMaybeEntryWriter->CurrentBlockIndex();
+ });
+ }
+
+ // Add a new single entry with *all* given object (using a Serializer for
+ // each), return block index.
+ template <typename... Ts>
+ ProfileBufferBlockIndex PutObjects(const Ts&... aTs) {
+ static_assert(sizeof...(Ts) > 0,
+ "PutObjects must be given at least one object.");
+ return ReserveAndPut(
+ [&]() { return ProfileBufferEntryWriter::SumBytes(aTs...); },
+ [&](Maybe<ProfileBufferEntryWriter>& aMaybeEntryWriter) {
+ if (aMaybeEntryWriter.isNothing()) {
+ return ProfileBufferBlockIndex{};
+ }
+ aMaybeEntryWriter->WriteObjects(aTs...);
+ return aMaybeEntryWriter->CurrentBlockIndex();
+ });
+ }
+
+ // Add a new entry copied from the given object, return block index.
+ template <typename T>
+ ProfileBufferBlockIndex PutObject(const T& aOb) {
+ return PutObjects(aOb);
+ }
+
+ // Get *all* chunks related to this buffer, including extant chunks in its
+ // ChunkManager, and yet-unused new/recycled chunks.
+ // We don't expect this buffer to be used again, though it's still possible
+ // and will allocate the first buffer when needed.
+ [[nodiscard]] UniquePtr<ProfileBufferChunk> GetAllChunks() {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return nullptr;
+ }
+ UniquePtr<ProfileBufferChunk> chunks =
+ mChunkManager->GetExtantReleasedChunks();
+ Unused << HandleRequestedChunk_IsPending(lock);
+ if (MOZ_LIKELY(!!mCurrentChunk)) {
+ mCurrentChunk->MarkDone();
+ chunks =
+ ProfileBufferChunk::Join(std::move(chunks), std::move(mCurrentChunk));
+ }
+ chunks =
+ ProfileBufferChunk::Join(std::move(chunks), std::move(mNextChunks));
+ mChunkManager->ForgetUnreleasedChunks();
+ mRangeStart = mRangeEnd = mNextChunkRangeStart;
+ return chunks;
+ }
+
+ // True if the given index points inside the current chunk (up to the last
+ // written byte).
+ // This could be used to check if an index written now would have a good
+ // chance of referring to a previous block that has not been destroyed yet.
+ // But use with extreme care: This information may become incorrect right
+ // after this function returns, because new writes could start a new chunk.
+ [[nodiscard]] bool IsIndexInCurrentChunk(ProfileBufferIndex aIndex) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager || !mCurrentChunk)) {
+ // Out-of-session, or no current chunk.
+ return false;
+ }
+ return (mCurrentChunk->RangeStart() <= aIndex) &&
+ (aIndex < (mCurrentChunk->RangeStart() +
+ mCurrentChunk->OffsetPastLastBlock()));
+ }
+
+ class Reader;
+
+ // Class that can iterate through blocks and provide
+ // `ProfileBufferEntryReader`s.
+ // Created through `Reader`, lives within a lock guard lifetime.
+ class BlockIterator {
+ public:
+#ifdef DEBUG
+ ~BlockIterator() {
+ // No BlockIterator should live outside of a mutexed call.
+ mBuffer->mMutex.AssertCurrentThreadOwns();
+ }
+#endif // DEBUG
+
+ // Comparison with other iterator, mostly used in range-for loops.
+ [[nodiscard]] bool operator==(const BlockIterator& aRhs) const {
+ MOZ_ASSERT(mBuffer == aRhs.mBuffer);
+ return mCurrentBlockIndex == aRhs.mCurrentBlockIndex;
+ }
+ [[nodiscard]] bool operator!=(const BlockIterator& aRhs) const {
+ MOZ_ASSERT(mBuffer == aRhs.mBuffer);
+ return mCurrentBlockIndex != aRhs.mCurrentBlockIndex;
+ }
+
+ // Advance to next BlockIterator.
+ BlockIterator& operator++() {
+ mBuffer->mMutex.AssertCurrentThreadOwns();
+ mCurrentBlockIndex =
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mNextBlockPointer.GlobalRangePosition());
+ mCurrentEntry =
+ mNextBlockPointer.EntryReader(mNextBlockPointer.ReadEntrySize());
+ return *this;
+ }
+
+ // Dereferencing creates a `ProfileBufferEntryReader` object for the entry
+ // inside this block.
+ // (Note: It would be possible to return a `const
+ // ProfileBufferEntryReader&`, but not useful in practice, because in most
+ // case the user will want to read, which is non-const.)
+ [[nodiscard]] ProfileBufferEntryReader operator*() const {
+ return mCurrentEntry;
+ }
+
+ // True if this iterator is just past the last entry.
+ [[nodiscard]] bool IsAtEnd() const {
+ return mCurrentEntry.RemainingBytes() == 0;
+ }
+
+ // Can be used as reference to come back to this entry with `GetEntryAt()`.
+ [[nodiscard]] ProfileBufferBlockIndex CurrentBlockIndex() const {
+ return mCurrentBlockIndex;
+ }
+
+ // Index past the end of this block, which is the start of the next block.
+ [[nodiscard]] ProfileBufferBlockIndex NextBlockIndex() const {
+ MOZ_ASSERT(!IsAtEnd());
+ return ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mNextBlockPointer.GlobalRangePosition());
+ }
+
+ // Index of the first block in the whole buffer.
+ [[nodiscard]] ProfileBufferBlockIndex BufferRangeStart() const {
+ mBuffer->mMutex.AssertCurrentThreadOwns();
+ return ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mBuffer->mRangeStart);
+ }
+
+ // Index past the last block in the whole buffer.
+ [[nodiscard]] ProfileBufferBlockIndex BufferRangeEnd() const {
+ mBuffer->mMutex.AssertCurrentThreadOwns();
+ return ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mBuffer->mRangeEnd);
+ }
+
+ private:
+ // Only a Reader can instantiate a BlockIterator.
+ friend class Reader;
+
+ BlockIterator(const ProfileChunkedBuffer& aBuffer,
+ const ProfileBufferChunk* aChunks0,
+ const ProfileBufferChunk* aChunks1,
+ ProfileBufferBlockIndex aBlockIndex)
+ : mNextBlockPointer(aChunks0, aChunks1, aBlockIndex),
+ mCurrentBlockIndex(
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mNextBlockPointer.GlobalRangePosition())),
+ mCurrentEntry(
+ mNextBlockPointer.EntryReader(mNextBlockPointer.ReadEntrySize())),
+ mBuffer(WrapNotNull(&aBuffer)) {
+ // No BlockIterator should live outside of a mutexed call.
+ mBuffer->mMutex.AssertCurrentThreadOwns();
+ }
+
+ profiler::detail::InChunkPointer mNextBlockPointer;
+
+ ProfileBufferBlockIndex mCurrentBlockIndex;
+
+ ProfileBufferEntryReader mCurrentEntry;
+
+ // Using a non-null pointer instead of a reference, to allow copying.
+ // This BlockIterator should only live inside one of the thread-safe
+ // ProfileChunkedBuffer functions, for this reference to stay valid.
+ NotNull<const ProfileChunkedBuffer*> mBuffer;
+ };
+
+ // Class that can create `BlockIterator`s (e.g., for range-for), or just
+ // iterate through entries; lives within a lock guard lifetime.
+ class MOZ_RAII Reader {
+ public:
+ Reader(const Reader&) = delete;
+ Reader& operator=(const Reader&) = delete;
+ Reader(Reader&&) = delete;
+ Reader& operator=(Reader&&) = delete;
+
+#ifdef DEBUG
+ ~Reader() {
+ // No Reader should live outside of a mutexed call.
+ mBuffer.mMutex.AssertCurrentThreadOwns();
+ }
+#endif // DEBUG
+
+ // Index of the first block in the whole buffer.
+ [[nodiscard]] ProfileBufferBlockIndex BufferRangeStart() const {
+ mBuffer.mMutex.AssertCurrentThreadOwns();
+ return ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mBuffer.mRangeStart);
+ }
+
+ // Index past the last block in the whole buffer.
+ [[nodiscard]] ProfileBufferBlockIndex BufferRangeEnd() const {
+ mBuffer.mMutex.AssertCurrentThreadOwns();
+ return ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ mBuffer.mRangeEnd);
+ }
+
+ // Iterators to the first and past-the-last blocks.
+ // Compatible with range-for (see `ForEach` below as example).
+ [[nodiscard]] BlockIterator begin() const {
+ return BlockIterator(mBuffer, mChunks0, mChunks1, nullptr);
+ }
+ // Note that a `BlockIterator` at the `end()` should not be dereferenced, as
+ // there is no actual block there!
+ [[nodiscard]] BlockIterator end() const {
+ return BlockIterator(mBuffer, nullptr, nullptr, nullptr);
+ }
+
+ // Get a `BlockIterator` at the given `ProfileBufferBlockIndex`, clamped to
+ // the stored range. Note that a `BlockIterator` at the `end()` should not
+ // be dereferenced, as there is no actual block there!
+ [[nodiscard]] BlockIterator At(ProfileBufferBlockIndex aBlockIndex) const {
+ if (aBlockIndex < BufferRangeStart()) {
+ // Anything before the range (including null ProfileBufferBlockIndex) is
+ // clamped at the beginning.
+ return begin();
+ }
+ // Otherwise we at least expect the index to be valid (pointing exactly at
+ // a live block, or just past the end.)
+ return BlockIterator(mBuffer, mChunks0, mChunks1, aBlockIndex);
+ }
+
+ // Run `aCallback(ProfileBufferEntryReader&)` on each entry from first to
+ // last. Callback should not store `ProfileBufferEntryReader`, as it may
+ // become invalid after this thread-safe call.
+ template <typename Callback>
+ void ForEach(Callback&& aCallback) const {
+ for (ProfileBufferEntryReader reader : *this) {
+ aCallback(reader);
+ }
+ }
+
+ // If this reader only points at one chunk with some data, this data will be
+ // exposed as a single entry.
+ [[nodiscard]] ProfileBufferEntryReader SingleChunkDataAsEntry() {
+ const ProfileBufferChunk* onlyNonEmptyChunk = nullptr;
+ for (const ProfileBufferChunk* chunkList : {mChunks0, mChunks1}) {
+ for (const ProfileBufferChunk* chunk = chunkList; chunk;
+ chunk = chunk->GetNext()) {
+ if (chunk->OffsetFirstBlock() != chunk->OffsetPastLastBlock()) {
+ if (onlyNonEmptyChunk) {
+ // More than one non-empty chunk.
+ return ProfileBufferEntryReader();
+ }
+ onlyNonEmptyChunk = chunk;
+ }
+ }
+ }
+ if (!onlyNonEmptyChunk) {
+ // No non-empty chunks.
+ return ProfileBufferEntryReader();
+ }
+ // Here, we have found one chunk that had some data.
+ return ProfileBufferEntryReader(
+ onlyNonEmptyChunk->BufferSpan().FromTo(
+ onlyNonEmptyChunk->OffsetFirstBlock(),
+ onlyNonEmptyChunk->OffsetPastLastBlock()),
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ onlyNonEmptyChunk->RangeStart()),
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ onlyNonEmptyChunk->RangeStart() +
+ (onlyNonEmptyChunk->OffsetPastLastBlock() -
+ onlyNonEmptyChunk->OffsetFirstBlock())));
+ }
+
+ private:
+ friend class ProfileChunkedBuffer;
+
+ explicit Reader(const ProfileChunkedBuffer& aBuffer,
+ const ProfileBufferChunk* aChunks0,
+ const ProfileBufferChunk* aChunks1)
+ : mBuffer(aBuffer), mChunks0(aChunks0), mChunks1(aChunks1) {
+ // No Reader should live outside of a mutexed call.
+ mBuffer.mMutex.AssertCurrentThreadOwns();
+ }
+
+ // This Reader should only live inside one of the thread-safe
+ // ProfileChunkedBuffer functions, for this reference to stay valid.
+ const ProfileChunkedBuffer& mBuffer;
+ const ProfileBufferChunk* mChunks0;
+ const ProfileBufferChunk* mChunks1;
+ };
+
+ // In in-session, call `aCallback(ProfileChunkedBuffer::Reader&)` and return
+ // true. Callback should not store `Reader`, because it may become invalid
+ // after this call.
+ // If out-of-session, return false (callback is not invoked).
+ template <typename Callback>
+ [[nodiscard]] auto Read(Callback&& aCallback) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return std::forward<Callback>(aCallback)(static_cast<Reader*>(nullptr));
+ }
+ return mChunkManager->PeekExtantReleasedChunks(
+ [&](const ProfileBufferChunk* aOldestChunk) {
+ Reader reader(*this, aOldestChunk, mCurrentChunk.get());
+ return std::forward<Callback>(aCallback)(&reader);
+ });
+ }
+
+ // Invoke `aCallback(ProfileBufferEntryReader& [, ProfileBufferBlockIndex])`
+ // on each entry, it must read or at least skip everything. Either/both chunk
+ // pointers may be null.
+ template <typename Callback>
+ static void ReadEach(const ProfileBufferChunk* aChunks0,
+ const ProfileBufferChunk* aChunks1,
+ Callback&& aCallback) {
+ static_assert(std::is_invocable_v<Callback, ProfileBufferEntryReader&> ||
+ std::is_invocable_v<Callback, ProfileBufferEntryReader&,
+ ProfileBufferBlockIndex>,
+ "ReadEach callback must take ProfileBufferEntryReader& and "
+ "optionally a ProfileBufferBlockIndex");
+ profiler::detail::InChunkPointer p{aChunks0, aChunks1};
+ while (!p.IsNull()) {
+ // The position right before an entry size *is* a block index.
+ const ProfileBufferBlockIndex blockIndex =
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ p.GlobalRangePosition());
+ Length entrySize = p.ReadEntrySize();
+ if (entrySize == 0) {
+ return;
+ }
+ ProfileBufferEntryReader entryReader = p.EntryReader(entrySize);
+ if (entryReader.RemainingBytes() == 0) {
+ return;
+ }
+ MOZ_ASSERT(entryReader.RemainingBytes() == entrySize);
+ if constexpr (std::is_invocable_v<Callback, ProfileBufferEntryReader&,
+ ProfileBufferBlockIndex>) {
+ aCallback(entryReader, blockIndex);
+ } else {
+ Unused << blockIndex;
+ aCallback(entryReader);
+ }
+ MOZ_ASSERT(entryReader.RemainingBytes() == 0);
+ }
+ }
+
+ // Invoke `aCallback(ProfileBufferEntryReader& [, ProfileBufferBlockIndex])`
+ // on each entry, it must read or at least skip everything.
+ template <typename Callback>
+ void ReadEach(Callback&& aCallback) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return;
+ }
+ mChunkManager->PeekExtantReleasedChunks(
+ [&](const ProfileBufferChunk* aOldestChunk) {
+ ReadEach(aOldestChunk, mCurrentChunk.get(),
+ std::forward<Callback>(aCallback));
+ });
+ }
+
+ // Call `aCallback(Maybe<ProfileBufferEntryReader>&&)` on the entry at
+ // the given ProfileBufferBlockIndex; The `Maybe` will be `Nothing` if
+ // out-of-session, or if that entry doesn't exist anymore, or if we've reached
+ // just past the last entry. Return whatever `aCallback` returns. Callback
+ // should not store `ProfileBufferEntryReader`, because it may become invalid
+ // after this call.
+ // Either/both chunk pointers may be null.
+ template <typename Callback>
+ [[nodiscard]] static auto ReadAt(ProfileBufferBlockIndex aMinimumBlockIndex,
+ const ProfileBufferChunk* aChunks0,
+ const ProfileBufferChunk* aChunks1,
+ Callback&& aCallback) {
+ static_assert(
+ std::is_invocable_v<Callback, Maybe<ProfileBufferEntryReader>&&>,
+ "ReadAt callback must take a Maybe<ProfileBufferEntryReader>&&");
+ Maybe<ProfileBufferEntryReader> maybeEntryReader;
+ if (profiler::detail::InChunkPointer p{aChunks0, aChunks1}; !p.IsNull()) {
+ // If the pointer position is before the given position, try to advance.
+ if (p.GlobalRangePosition() >=
+ aMinimumBlockIndex.ConvertToProfileBufferIndex() ||
+ p.AdvanceToGlobalRangePosition(
+ aMinimumBlockIndex.ConvertToProfileBufferIndex())) {
+ MOZ_ASSERT(p.GlobalRangePosition() >=
+ aMinimumBlockIndex.ConvertToProfileBufferIndex());
+ // Here we're pointing at the start of a block, try to read the entry
+ // size. (Entries cannot be empty, so 0 means failure.)
+ if (Length entrySize = p.ReadEntrySize(); entrySize != 0) {
+ maybeEntryReader.emplace(p.EntryReader(entrySize));
+ if (maybeEntryReader->RemainingBytes() == 0) {
+ // An empty entry reader means there was no complete block at the
+ // given index.
+ maybeEntryReader.reset();
+ } else {
+ MOZ_ASSERT(maybeEntryReader->RemainingBytes() == entrySize);
+ }
+ }
+ }
+ }
+#ifdef DEBUG
+ auto assertAllRead = MakeScopeExit([&]() {
+ MOZ_ASSERT(!maybeEntryReader || maybeEntryReader->RemainingBytes() == 0);
+ });
+#endif // DEBUG
+ return std::forward<Callback>(aCallback)(std::move(maybeEntryReader));
+ }
+
+ // Call `aCallback(Maybe<ProfileBufferEntryReader>&&)` on the entry at
+ // the given ProfileBufferBlockIndex; The `Maybe` will be `Nothing` if
+ // out-of-session, or if that entry doesn't exist anymore, or if we've reached
+ // just past the last entry. Return whatever `aCallback` returns. Callback
+ // should not store `ProfileBufferEntryReader`, because it may become invalid
+ // after this call.
+ template <typename Callback>
+ [[nodiscard]] auto ReadAt(ProfileBufferBlockIndex aBlockIndex,
+ Callback&& aCallback) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return std::forward<Callback>(aCallback)(Nothing{});
+ }
+ return mChunkManager->PeekExtantReleasedChunks(
+ [&](const ProfileBufferChunk* aOldestChunk) {
+ return ReadAt(aBlockIndex, aOldestChunk, mCurrentChunk.get(),
+ std::forward<Callback>(aCallback));
+ });
+ }
+
+ // Append the contents of another ProfileChunkedBuffer to this one.
+ ProfileBufferBlockIndex AppendContents(const ProfileChunkedBuffer& aSrc) {
+ ProfileBufferBlockIndex firstBlockIndex;
+ // If we start failing, we'll stop writing.
+ bool failed = false;
+ aSrc.ReadEach([&](ProfileBufferEntryReader& aER) {
+ if (failed) {
+ return;
+ }
+ failed =
+ !Put(aER.RemainingBytes(), [&](Maybe<ProfileBufferEntryWriter>& aEW) {
+ if (aEW.isNothing()) {
+ return false;
+ }
+ if (!firstBlockIndex) {
+ firstBlockIndex = aEW->CurrentBlockIndex();
+ }
+ aEW->WriteFromReader(aER, aER.RemainingBytes());
+ return true;
+ });
+ });
+ return failed ? nullptr : firstBlockIndex;
+ }
+
+#ifdef DEBUG
+ void Dump(std::FILE* aFile = stdout) const {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ fprintf(aFile,
+ "ProfileChunkedBuffer[%p] State: range %u-%u pushed=%u cleared=%u "
+ "(live=%u) failed-puts=%u bytes",
+ this, unsigned(mRangeStart), unsigned(mRangeEnd),
+ unsigned(mPushedBlockCount), unsigned(mClearedBlockCount),
+ unsigned(mPushedBlockCount) - unsigned(mClearedBlockCount),
+ unsigned(mFailedPutBytes));
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ fprintf(aFile, " - Out-of-session\n");
+ return;
+ }
+ fprintf(aFile, " - chunks:\n");
+ bool hasChunks = false;
+ mChunkManager->PeekExtantReleasedChunks(
+ [&](const ProfileBufferChunk* aOldestChunk) {
+ for (const ProfileBufferChunk* chunk = aOldestChunk; chunk;
+ chunk = chunk->GetNext()) {
+ fprintf(aFile, "R ");
+ chunk->Dump(aFile);
+ hasChunks = true;
+ }
+ });
+ if (mCurrentChunk) {
+ fprintf(aFile, "C ");
+ mCurrentChunk->Dump(aFile);
+ hasChunks = true;
+ }
+ for (const ProfileBufferChunk* chunk = mNextChunks.get(); chunk;
+ chunk = chunk->GetNext()) {
+ fprintf(aFile, "N ");
+ chunk->Dump(aFile);
+ hasChunks = true;
+ }
+ switch (mRequestedChunkHolder->GetState()) {
+ case RequestedChunkRefCountedHolder::State::Unused:
+ fprintf(aFile, " - No request pending.\n");
+ break;
+ case RequestedChunkRefCountedHolder::State::Requested:
+ fprintf(aFile, " - Request pending.\n");
+ break;
+ case RequestedChunkRefCountedHolder::State::Fulfilled:
+ fprintf(aFile, " - Request fulfilled.\n");
+ break;
+ }
+ if (!hasChunks) {
+ fprintf(aFile, " No chunks.\n");
+ }
+ }
+#endif // DEBUG
+
+ private:
+ // Used to de/serialize a ProfileChunkedBuffer (e.g., containing a backtrace).
+ friend ProfileBufferEntryWriter::Serializer<ProfileChunkedBuffer>;
+ friend ProfileBufferEntryReader::Deserializer<ProfileChunkedBuffer>;
+ friend ProfileBufferEntryWriter::Serializer<UniquePtr<ProfileChunkedBuffer>>;
+ friend ProfileBufferEntryReader::Deserializer<
+ UniquePtr<ProfileChunkedBuffer>>;
+
+ [[nodiscard]] UniquePtr<ProfileBufferChunkManager> ResetChunkManager(
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock&) {
+ UniquePtr<ProfileBufferChunkManager> chunkManager;
+ if (mChunkManager) {
+ mRequestedChunkHolder = nullptr;
+ mChunkManager->ForgetUnreleasedChunks();
+#ifdef DEBUG
+ mChunkManager->DeregisteredFrom(this);
+#endif
+ mChunkManager = nullptr;
+ chunkManager = std::move(mOwnedChunkManager);
+ if (mCurrentChunk) {
+ mCurrentChunk->MarkDone();
+ mCurrentChunk = nullptr;
+ }
+ mNextChunks = nullptr;
+ mNextChunkRangeStart = mRangeEnd;
+ mRangeStart = mRangeEnd;
+ mPushedBlockCount = 0;
+ mClearedBlockCount = 0;
+ mFailedPutBytes = 0;
+ }
+ return chunkManager;
+ }
+
+ void SetChunkManager(
+ ProfileBufferChunkManager& aChunkManager,
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock) {
+ MOZ_ASSERT(!mChunkManager);
+ mChunkManager = &aChunkManager;
+#ifdef DEBUG
+ mChunkManager->RegisteredWith(this);
+#endif
+
+ mChunkManager->SetChunkDestroyedCallback(
+ [this](const ProfileBufferChunk& aChunk) {
+ for (;;) {
+ ProfileBufferIndex rangeStart = mRangeStart;
+ if (MOZ_LIKELY(rangeStart <= aChunk.RangeStart())) {
+ if (MOZ_LIKELY(mRangeStart.compareExchange(
+ rangeStart,
+ aChunk.RangeStart() + aChunk.BufferBytes()))) {
+ break;
+ }
+ }
+ }
+ mClearedBlockCount += aChunk.BlockCount();
+ });
+
+ // We start with one chunk right away, and request a following one now
+ // so it should be available before the current chunk is full.
+ SetAndInitializeCurrentChunk(mChunkManager->GetChunk(), aLock);
+ mRequestedChunkHolder = MakeRefPtr<RequestedChunkRefCountedHolder>();
+ RequestChunk(aLock);
+ }
+
+ [[nodiscard]] size_t SizeOfExcludingThis(
+ MallocSizeOf aMallocSizeOf,
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock&) const {
+ if (MOZ_UNLIKELY(!mChunkManager)) {
+ // Out-of-session.
+ return 0;
+ }
+ size_t size = mChunkManager->SizeOfIncludingThis(aMallocSizeOf);
+ if (mCurrentChunk) {
+ size += mCurrentChunk->SizeOfIncludingThis(aMallocSizeOf);
+ }
+ if (mNextChunks) {
+ size += mNextChunks->SizeOfIncludingThis(aMallocSizeOf);
+ }
+ return size;
+ }
+
+ void InitializeCurrentChunk(
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock&) {
+ MOZ_ASSERT(!!mCurrentChunk);
+ mCurrentChunk->SetRangeStart(mNextChunkRangeStart);
+ mNextChunkRangeStart += mCurrentChunk->BufferBytes();
+ Unused << mCurrentChunk->ReserveInitialBlockAsTail(0);
+ }
+
+ void SetAndInitializeCurrentChunk(
+ UniquePtr<ProfileBufferChunk>&& aChunk,
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock) {
+ mCurrentChunk = std::move(aChunk);
+ if (mCurrentChunk) {
+ InitializeCurrentChunk(aLock);
+ }
+ }
+
+ void RequestChunk(
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock) {
+ if (HandleRequestedChunk_IsPending(aLock)) {
+ // There is already a pending request, don't start a new one.
+ return;
+ }
+
+ // Ensure the `RequestedChunkHolder` knows we're starting a request.
+ mRequestedChunkHolder->StartRequest();
+
+ // Request a chunk, the callback carries a `RefPtr` of the
+ // `RequestedChunkHolder`, so it's guaranteed to live until it's invoked,
+ // even if this `ProfileChunkedBuffer` changes its `ChunkManager` or is
+ // destroyed.
+ mChunkManager->RequestChunk(
+ [requestedChunkHolder = RefPtr<RequestedChunkRefCountedHolder>(
+ mRequestedChunkHolder)](UniquePtr<ProfileBufferChunk> aChunk) {
+ requestedChunkHolder->AddRequestedChunk(std::move(aChunk));
+ });
+ }
+
+ [[nodiscard]] bool HandleRequestedChunk_IsPending(
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock) {
+ MOZ_ASSERT(!!mChunkManager);
+ MOZ_ASSERT(!!mRequestedChunkHolder);
+
+ if (mRequestedChunkHolder->GetState() ==
+ RequestedChunkRefCountedHolder::State::Unused) {
+ return false;
+ }
+
+ // A request is either in-flight or fulfilled.
+ Maybe<UniquePtr<ProfileBufferChunk>> maybeChunk =
+ mRequestedChunkHolder->GetChunkIfFulfilled();
+ if (maybeChunk.isNothing()) {
+ // Request is still pending.
+ return true;
+ }
+
+ // Since we extracted the provided chunk, the holder should now be unused.
+ MOZ_ASSERT(mRequestedChunkHolder->GetState() ==
+ RequestedChunkRefCountedHolder::State::Unused);
+
+ // Request has been fulfilled.
+ UniquePtr<ProfileBufferChunk>& chunk = *maybeChunk;
+ if (chunk) {
+ // Try to use as current chunk if needed.
+ if (!mCurrentChunk) {
+ SetAndInitializeCurrentChunk(std::move(chunk), aLock);
+ // We've just received a chunk and made it current, request a next chunk
+ // for later.
+ MOZ_ASSERT(!mNextChunks);
+ RequestChunk(aLock);
+ return true;
+ }
+
+ if (!mNextChunks) {
+ mNextChunks = std::move(chunk);
+ } else {
+ mNextChunks->InsertNext(std::move(chunk));
+ }
+ }
+
+ return false;
+ }
+
+ // Get a pointer to the next chunk available
+ [[nodiscard]] ProfileBufferChunk* GetOrCreateCurrentChunk(
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock) {
+ ProfileBufferChunk* current = mCurrentChunk.get();
+ if (MOZ_UNLIKELY(!current)) {
+ // No current chunk ready.
+ MOZ_ASSERT(!mNextChunks,
+ "There shouldn't be next chunks when there is no current one");
+ // See if a request has recently been fulfilled, ignore pending status.
+ Unused << HandleRequestedChunk_IsPending(aLock);
+ current = mCurrentChunk.get();
+ if (MOZ_UNLIKELY(!current)) {
+ // There was no pending chunk, try to get one right now.
+ // This may still fail, but we can't do anything else about it, the
+ // caller must handle the nullptr case.
+ // Attempt a request for later.
+ SetAndInitializeCurrentChunk(mChunkManager->GetChunk(), aLock);
+ current = mCurrentChunk.get();
+ }
+ }
+ return current;
+ }
+
+ // Get a pointer to the next chunk available
+ [[nodiscard]] ProfileBufferChunk* GetOrCreateNextChunk(
+ const baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock) {
+ MOZ_ASSERT(!!mCurrentChunk,
+ "Why ask for a next chunk when there isn't even a current one?");
+ ProfileBufferChunk* next = mNextChunks.get();
+ if (MOZ_UNLIKELY(!next)) {
+ // No next chunk ready, see if a request has recently been fulfilled,
+ // ignore pending status.
+ Unused << HandleRequestedChunk_IsPending(aLock);
+ next = mNextChunks.get();
+ if (MOZ_UNLIKELY(!next)) {
+ // There was no pending chunk, try to get one right now.
+ mNextChunks = mChunkManager->GetChunk();
+ next = mNextChunks.get();
+ // This may still fail, but we can't do anything else about it, the
+ // caller must handle the nullptr case.
+ if (MOZ_UNLIKELY(!next)) {
+ // Attempt a request for later.
+ RequestChunk(aLock);
+ }
+ }
+ }
+ return next;
+ }
+
+ // Reserve a block of `aCallbackBlockBytes()` size, and invoke and return
+ // `aCallback(Maybe<ProfileBufferEntryWriter>&)`. Note that this is the "raw"
+ // version that doesn't write the entry size at the beginning of the block.
+ // Note: `aCallbackBlockBytes` is a callback instead of a simple value, to
+ // delay this potentially-expensive computation until after we're checked that
+ // we're in-session; use `Put(Length, Callback)` below if you know the size
+ // already.
+ template <typename CallbackBlockBytes, typename Callback>
+ auto ReserveAndPutRaw(CallbackBlockBytes&& aCallbackBlockBytes,
+ Callback&& aCallback,
+ baseprofiler::detail::BaseProfilerMaybeAutoLock& aLock,
+ uint64_t aBlockCount = 1) {
+ // The entry writer that will point into one or two chunks to write
+ // into, empty by default (failure).
+ Maybe<ProfileBufferEntryWriter> maybeEntryWriter;
+
+ // The current chunk will be filled if we need to write more than its
+ // remaining space.
+ bool currentChunkFilled = false;
+
+ // If the current chunk gets filled, we may or may not initialize the next
+ // chunk!
+ bool nextChunkInitialized = false;
+
+ if (MOZ_LIKELY(mChunkManager)) {
+ // In-session.
+
+ const Length blockBytes =
+ std::forward<CallbackBlockBytes>(aCallbackBlockBytes)();
+
+ if (ProfileBufferChunk* current = GetOrCreateCurrentChunk(aLock);
+ MOZ_LIKELY(current)) {
+ if (blockBytes <= current->RemainingBytes()) {
+ // Block fits in current chunk with only one span.
+ currentChunkFilled = blockBytes == current->RemainingBytes();
+ const auto [mem0, blockIndex] = current->ReserveBlock(blockBytes);
+ MOZ_ASSERT(mem0.LengthBytes() == blockBytes);
+ maybeEntryWriter.emplace(
+ mem0, blockIndex,
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ blockIndex.ConvertToProfileBufferIndex() + blockBytes));
+ MOZ_ASSERT(maybeEntryWriter->RemainingBytes() == blockBytes);
+ mRangeEnd += blockBytes;
+ mPushedBlockCount += aBlockCount;
+ } else if (blockBytes >= current->BufferBytes()) {
+ // Currently only two buffer chunks are held at a time and it is not
+ // possible to write an object that takes up more space than this. In
+ // this scenario, silently discard this block of data if it is unable
+ // to fit into the two reserved profiler chunks.
+ mFailedPutBytes += blockBytes;
+ } else {
+ // Block doesn't fit fully in current chunk, it needs to overflow into
+ // the next one.
+ // Whether or not we can write this entry, the current chunk is now
+ // considered full, so it will be released. (Otherwise we could refuse
+ // this entry, but later accept a smaller entry into this chunk, which
+ // would be somewhat inconsistent.)
+ currentChunkFilled = true;
+ // Make sure the next chunk is available (from a previous request),
+ // otherwise create one on the spot.
+ if (ProfileBufferChunk* next = GetOrCreateNextChunk(aLock);
+ MOZ_LIKELY(next)) {
+ // Here, we know we have a current and a next chunk.
+ // Reserve head of block at the end of the current chunk.
+ const auto [mem0, blockIndex] =
+ current->ReserveBlock(current->RemainingBytes());
+ MOZ_ASSERT(mem0.LengthBytes() < blockBytes);
+ MOZ_ASSERT(current->RemainingBytes() == 0);
+ // Set the next chunk range, and reserve the needed space for the
+ // tail of the block.
+ next->SetRangeStart(mNextChunkRangeStart);
+ mNextChunkRangeStart += next->BufferBytes();
+ const auto mem1 = next->ReserveInitialBlockAsTail(
+ blockBytes - mem0.LengthBytes());
+ MOZ_ASSERT(next->RemainingBytes() != 0);
+ nextChunkInitialized = true;
+ // Block is split in two spans.
+ maybeEntryWriter.emplace(
+ mem0, mem1, blockIndex,
+ ProfileBufferBlockIndex::CreateFromProfileBufferIndex(
+ blockIndex.ConvertToProfileBufferIndex() + blockBytes));
+ MOZ_ASSERT(maybeEntryWriter->RemainingBytes() == blockBytes);
+ mRangeEnd += blockBytes;
+ mPushedBlockCount += aBlockCount;
+ } else {
+ // Cannot get a new chunk. Record put failure.
+ mFailedPutBytes += blockBytes;
+ }
+ }
+ } else {
+ // Cannot get a current chunk. Record put failure.
+ mFailedPutBytes += blockBytes;
+ }
+ } // end of `if (MOZ_LIKELY(mChunkManager))`
+
+ // Here, we either have a `Nothing` (failure), or a non-empty entry writer
+ // pointing at the start of the block.
+
+ // After we invoke the callback and return, we may need to handle the
+ // current chunk being filled.
+ auto handleFilledChunk = MakeScopeExit([&]() {
+ // If the entry writer was not already empty, the callback *must* have
+ // filled the full entry.
+ MOZ_ASSERT(!maybeEntryWriter || maybeEntryWriter->RemainingBytes() == 0);
+
+ if (currentChunkFilled) {
+ // Extract current (now filled) chunk.
+ UniquePtr<ProfileBufferChunk> filled = std::move(mCurrentChunk);
+
+ if (mNextChunks) {
+ // Cycle to the next chunk.
+ mCurrentChunk =
+ std::exchange(mNextChunks, mNextChunks->ReleaseNext());
+
+ // Make sure it is initialized (it is now the current chunk).
+ if (!nextChunkInitialized) {
+ InitializeCurrentChunk(aLock);
+ }
+ }
+
+ // And finally mark filled chunk done and release it.
+ filled->MarkDone();
+ mChunkManager->ReleaseChunk(std::move(filled));
+
+ // Request another chunk if needed.
+ // In most cases, here we should have one current chunk and no next
+ // chunk, so we want to do a request so there hopefully will be a next
+ // chunk available when the current one gets filled.
+ // But we also for a request if we don't even have a current chunk (if
+ // it's too late, it's ok because the next `ReserveAndPutRaw` wil just
+ // allocate one on the spot.)
+ // And if we already have a next chunk, there's no need for more now.
+ if (!mCurrentChunk || !mNextChunks) {
+ RequestChunk(aLock);
+ }
+ }
+ });
+
+ return std::forward<Callback>(aCallback)(maybeEntryWriter);
+ }
+
+ // Reserve a block of `aBlockBytes` size, and invoke and return
+ // `aCallback(Maybe<ProfileBufferEntryWriter>&)`. Note that this is the "raw"
+ // version that doesn't write the entry size at the beginning of the block.
+ template <typename Callback>
+ auto ReserveAndPutRaw(Length aBlockBytes, Callback&& aCallback,
+ uint64_t aBlockCount) {
+ baseprofiler::detail::BaseProfilerMaybeAutoLock lock(mMutex);
+ return ReserveAndPutRaw([aBlockBytes]() { return aBlockBytes; },
+ std::forward<Callback>(aCallback), lock,
+ aBlockCount);
+ }
+
+ // Mutex guarding the following members.
+ mutable baseprofiler::detail::BaseProfilerMaybeMutex mMutex;
+
+ // Pointer to the current Chunk Manager (or null when out-of-session.)
+ // It may be owned locally (see below) or externally.
+ ProfileBufferChunkManager* mChunkManager = nullptr;
+
+ // Only non-null when we own the current Chunk Manager.
+ UniquePtr<ProfileBufferChunkManager> mOwnedChunkManager;
+
+ UniquePtr<ProfileBufferChunk> mCurrentChunk;
+
+ UniquePtr<ProfileBufferChunk> mNextChunks;
+
+ // Class used to transfer requested chunks from a `ChunkManager` to a
+ // `ProfileChunkedBuffer`.
+ // It needs to be ref-counted because the request may be fulfilled
+ // asynchronously, and either side may be destroyed during the request.
+ // It cannot use the `ProfileChunkedBuffer` mutex, because that buffer and its
+ // mutex could be destroyed during the request.
+ class RequestedChunkRefCountedHolder {
+ public:
+ enum class State { Unused, Requested, Fulfilled };
+
+ // Get the current state. Note that it may change after the function
+ // returns, so it should be used carefully, e.g., `ProfileChunkedBuffer` can
+ // see if a request is pending or fulfilled, to avoid starting another
+ // request.
+ [[nodiscard]] State GetState() const {
+ baseprofiler::detail::BaseProfilerAutoLock lock(mRequestMutex);
+ return mState;
+ }
+
+ // Must be called by `ProfileChunkedBuffer` when it requests a chunk.
+ // There cannot be more than one request in-flight.
+ void StartRequest() {
+ baseprofiler::detail::BaseProfilerAutoLock lock(mRequestMutex);
+ MOZ_ASSERT(mState == State::Unused, "Already requested or fulfilled");
+ mState = State::Requested;
+ }
+
+ // Must be called by the `ChunkManager` with a chunk.
+ // If the `ChunkManager` cannot provide a chunk (because of memory limits,
+ // or it gets destroyed), it must call this anyway with a nullptr.
+ void AddRequestedChunk(UniquePtr<ProfileBufferChunk>&& aChunk) {
+ baseprofiler::detail::BaseProfilerAutoLock lock(mRequestMutex);
+ MOZ_ASSERT(mState == State::Requested);
+ mState = State::Fulfilled;
+ mRequestedChunk = std::move(aChunk);
+ }
+
+ // The `ProfileChunkedBuffer` can try to extract the provided chunk after a
+ // request:
+ // - Nothing -> Request is not fulfilled yet.
+ // - Some(nullptr) -> The `ChunkManager` was not able to provide a chunk.
+ // - Some(chunk) -> Requested chunk.
+ [[nodiscard]] Maybe<UniquePtr<ProfileBufferChunk>> GetChunkIfFulfilled() {
+ Maybe<UniquePtr<ProfileBufferChunk>> maybeChunk;
+ baseprofiler::detail::BaseProfilerAutoLock lock(mRequestMutex);
+ MOZ_ASSERT(mState == State::Requested || mState == State::Fulfilled);
+ if (mState == State::Fulfilled) {
+ mState = State::Unused;
+ maybeChunk.emplace(std::move(mRequestedChunk));
+ }
+ return maybeChunk;
+ }
+
+ // Ref-counting implementation. Hand-rolled, because mozilla::RefCounted
+ // logs AddRefs and Releases in xpcom, but this object could be AddRef'd
+ // by the Base Profiler before xpcom starts, then Release'd by the Gecko
+ // Profiler in xpcom, leading to apparent negative leaks.
+
+ void AddRef() {
+ baseprofiler::detail::BaseProfilerAutoLock lock(mRequestMutex);
+ ++mRefCount;
+ }
+
+ void Release() {
+ {
+ baseprofiler::detail::BaseProfilerAutoLock lock(mRequestMutex);
+ if (--mRefCount > 0) {
+ return;
+ }
+ }
+ delete this;
+ }
+
+ private:
+ ~RequestedChunkRefCountedHolder() = default;
+
+ // Mutex guarding the following members.
+ mutable baseprofiler::detail::BaseProfilerMutex mRequestMutex;
+ int mRefCount = 0;
+ State mState = State::Unused;
+ UniquePtr<ProfileBufferChunk> mRequestedChunk;
+ };
+
+ // Requested-chunk holder, kept alive when in-session, but may also live
+ // longer if a request is in-flight.
+ RefPtr<RequestedChunkRefCountedHolder> mRequestedChunkHolder;
+
+ // Range start of the next chunk to become current. Starting at 1 because
+ // 0 is a reserved index similar to nullptr.
+ ProfileBufferIndex mNextChunkRangeStart = 1;
+
+ // Index to the first block.
+ // Atomic because it may be increased when a Chunk is destroyed, and the
+ // callback may be invoked from anywhere, including from inside one of our
+ // locked section, so we cannot protect it with a mutex.
+ Atomic<ProfileBufferIndex, MemoryOrdering::ReleaseAcquire> mRangeStart{1};
+
+ // Index past the last block. Equals mRangeStart if empty.
+ ProfileBufferIndex mRangeEnd = 1;
+
+ // Number of blocks that have been pushed into this buffer.
+ uint64_t mPushedBlockCount = 0;
+
+ // Number of blocks that have been removed from this buffer.
+ // Note: Live entries = pushed - cleared.
+ // Atomic because it may be updated when a Chunk is destroyed, and the
+ // callback may be invoked from anywhere, including from inside one of our
+ // locked section, so we cannot protect it with a mutex.
+ Atomic<uint64_t, MemoryOrdering::ReleaseAcquire> mClearedBlockCount{0};
+
+ // Number of bytes that could not be put into this buffer.
+ uint64_t mFailedPutBytes = 0;
+};
+
+// ----------------------------------------------------------------------------
+// ProfileChunkedBuffer serialization
+
+// A ProfileChunkedBuffer can hide another one!
+// This will be used to store marker backtraces; They can be read back into a
+// UniquePtr<ProfileChunkedBuffer>.
+// Format: len (ULEB128) | start | end | buffer (len bytes) | pushed | cleared
+// len==0 marks an out-of-session buffer, or empty buffer.
+template <>
+struct ProfileBufferEntryWriter::Serializer<ProfileChunkedBuffer> {
+ static Length Bytes(const ProfileChunkedBuffer& aBuffer) {
+ return aBuffer.Read([&](ProfileChunkedBuffer::Reader* aReader) {
+ if (!aReader) {
+ // Out-of-session, we only need 1 byte to store a length of 0.
+ return ULEB128Size<Length>(0);
+ }
+ ProfileBufferEntryReader reader = aReader->SingleChunkDataAsEntry();
+ const ProfileBufferIndex start =
+ reader.CurrentBlockIndex().ConvertToProfileBufferIndex();
+ const ProfileBufferIndex end =
+ reader.NextBlockIndex().ConvertToProfileBufferIndex();
+ MOZ_ASSERT(end - start <= std::numeric_limits<Length>::max());
+ const Length len = static_cast<Length>(end - start);
+ if (len == 0) {
+ // In-session but empty, also store a length of 0.
+ return ULEB128Size<Length>(0);
+ }
+ // In-session.
+ return static_cast<Length>(ULEB128Size(len) + sizeof(start) + len +
+ sizeof(aBuffer.mPushedBlockCount) +
+ sizeof(aBuffer.mClearedBlockCount));
+ });
+ }
+
+ static void Write(ProfileBufferEntryWriter& aEW,
+ const ProfileChunkedBuffer& aBuffer) {
+ aBuffer.Read([&](ProfileChunkedBuffer::Reader* aReader) {
+ if (!aReader) {
+ // Out-of-session, only store a length of 0.
+ aEW.WriteULEB128<Length>(0);
+ return;
+ }
+ ProfileBufferEntryReader reader = aReader->SingleChunkDataAsEntry();
+ const ProfileBufferIndex start =
+ reader.CurrentBlockIndex().ConvertToProfileBufferIndex();
+ const ProfileBufferIndex end =
+ reader.NextBlockIndex().ConvertToProfileBufferIndex();
+ MOZ_ASSERT(end - start <= std::numeric_limits<Length>::max());
+ const Length len = static_cast<Length>(end - start);
+ MOZ_ASSERT(len <= aEW.RemainingBytes());
+ if (len == 0) {
+ // In-session but empty, only store a length of 0.
+ aEW.WriteULEB128<Length>(0);
+ return;
+ }
+ // In-session.
+ // Store buffer length, and start index.
+ aEW.WriteULEB128(len);
+ aEW.WriteObject(start);
+ // Write all the bytes.
+ aEW.WriteFromReader(reader, reader.RemainingBytes());
+ // And write stats.
+ aEW.WriteObject(static_cast<uint64_t>(aBuffer.mPushedBlockCount));
+ aEW.WriteObject(static_cast<uint64_t>(aBuffer.mClearedBlockCount));
+ // Note: Failed pushes are not important to serialize.
+ });
+ }
+};
+
+// A serialized ProfileChunkedBuffer can be read into an empty buffer (either
+// out-of-session, or in-session with enough room).
+template <>
+struct ProfileBufferEntryReader::Deserializer<ProfileChunkedBuffer> {
+ static void ReadInto(ProfileBufferEntryReader& aER,
+ ProfileChunkedBuffer& aBuffer) {
+ // Expect an empty buffer, as we're going to overwrite it.
+ MOZ_ASSERT(aBuffer.GetState().mRangeStart == aBuffer.GetState().mRangeEnd);
+ // Read the stored buffer length.
+ const auto len = aER.ReadULEB128<ProfileChunkedBuffer::Length>();
+ if (len == 0) {
+ // 0-length means an "uninteresting" buffer, just return now.
+ return;
+ }
+ // We have a non-empty buffer to read.
+
+ // Read start and end indices.
+ const auto start = aER.ReadObject<ProfileBufferIndex>();
+ aBuffer.mRangeStart = start;
+ // For now, set the end to be the start (the buffer is still empty). It will
+ // be updated in `ReserveAndPutRaw()` below.
+ aBuffer.mRangeEnd = start;
+
+ if (aBuffer.IsInSession()) {
+ // Output buffer is in-session (i.e., it already has a memory buffer
+ // attached). Make sure the caller allocated enough space.
+ MOZ_RELEASE_ASSERT(aBuffer.BufferLength().value() >= len);
+ } else {
+ // Output buffer is out-of-session, set a new chunk manager that will
+ // provide a single chunk of just the right size.
+ aBuffer.SetChunkManager(MakeUnique<ProfileBufferChunkManagerSingle>(len));
+ MOZ_ASSERT(aBuffer.BufferLength().value() >= len);
+ }
+
+ // Copy bytes into the buffer.
+ aBuffer.ReserveAndPutRaw(
+ len,
+ [&](Maybe<ProfileBufferEntryWriter>& aEW) {
+ MOZ_RELEASE_ASSERT(aEW.isSome());
+ aEW->WriteFromReader(aER, len);
+ },
+ 0);
+ // Finally copy stats.
+ aBuffer.mPushedBlockCount = aER.ReadObject<uint64_t>();
+ aBuffer.mClearedBlockCount = aER.ReadObject<uint64_t>();
+ // Failed puts are not important to keep.
+ aBuffer.mFailedPutBytes = 0;
+ }
+
+ // We cannot output a ProfileChunkedBuffer object (not copyable), use
+ // `ReadInto()` or `aER.ReadObject<UniquePtr<BlocksRinbBuffer>>()` instead.
+ static ProfileChunkedBuffer Read(ProfileBufferEntryReader& aER) = delete;
+};
+
+// A ProfileChunkedBuffer is usually refererenced through a UniquePtr, for
+// convenience we support (de)serializing that UniquePtr directly.
+// This is compatible with the non-UniquePtr serialization above, with a null
+// pointer being treated like an out-of-session or empty buffer; and any of
+// these would be deserialized into a null pointer.
+template <>
+struct ProfileBufferEntryWriter::Serializer<UniquePtr<ProfileChunkedBuffer>> {
+ static Length Bytes(const UniquePtr<ProfileChunkedBuffer>& aBufferUPtr) {
+ if (!aBufferUPtr) {
+ // Null pointer, treat it like an empty buffer, i.e., write length of 0.
+ return ULEB128Size<Length>(0);
+ }
+ // Otherwise write the pointed-at ProfileChunkedBuffer (which could be
+ // out-of-session or empty.)
+ return SumBytes(*aBufferUPtr);
+ }
+
+ static void Write(ProfileBufferEntryWriter& aEW,
+ const UniquePtr<ProfileChunkedBuffer>& aBufferUPtr) {
+ if (!aBufferUPtr) {
+ // Null pointer, treat it like an empty buffer, i.e., write length of 0.
+ aEW.WriteULEB128<Length>(0);
+ return;
+ }
+ // Otherwise write the pointed-at ProfileChunkedBuffer (which could be
+ // out-of-session or empty.)
+ aEW.WriteObject(*aBufferUPtr);
+ }
+};
+
+// Serialization of a raw pointer to ProfileChunkedBuffer.
+// Use Deserializer<UniquePtr<ProfileChunkedBuffer>> to read it back.
+template <>
+struct ProfileBufferEntryWriter::Serializer<ProfileChunkedBuffer*> {
+ static Length Bytes(ProfileChunkedBuffer* aBufferUPtr) {
+ if (!aBufferUPtr) {
+ // Null pointer, treat it like an empty buffer, i.e., write length of 0.
+ return ULEB128Size<Length>(0);
+ }
+ // Otherwise write the pointed-at ProfileChunkedBuffer (which could be
+ // out-of-session or empty.)
+ return SumBytes(*aBufferUPtr);
+ }
+
+ static void Write(ProfileBufferEntryWriter& aEW,
+ ProfileChunkedBuffer* aBufferUPtr) {
+ if (!aBufferUPtr) {
+ // Null pointer, treat it like an empty buffer, i.e., write length of 0.
+ aEW.WriteULEB128<Length>(0);
+ return;
+ }
+ // Otherwise write the pointed-at ProfileChunkedBuffer (which could be
+ // out-of-session or empty.)
+ aEW.WriteObject(*aBufferUPtr);
+ }
+};
+
+template <>
+struct ProfileBufferEntryReader::Deserializer<UniquePtr<ProfileChunkedBuffer>> {
+ static void ReadInto(ProfileBufferEntryReader& aER,
+ UniquePtr<ProfileChunkedBuffer>& aBuffer) {
+ aBuffer = Read(aER);
+ }
+
+ static UniquePtr<ProfileChunkedBuffer> Read(ProfileBufferEntryReader& aER) {
+ UniquePtr<ProfileChunkedBuffer> bufferUPtr;
+ // Keep a copy of the reader before reading the length, so we can restart
+ // from here below.
+ ProfileBufferEntryReader readerBeforeLen = aER;
+ // Read the stored buffer length.
+ const auto len = aER.ReadULEB128<ProfileChunkedBuffer::Length>();
+ if (len == 0) {
+ // 0-length means an "uninteresting" buffer, just return nullptr.
+ return bufferUPtr;
+ }
+ // We have a non-empty buffer.
+ // allocate an empty ProfileChunkedBuffer without mutex.
+ bufferUPtr = MakeUnique<ProfileChunkedBuffer>(
+ ProfileChunkedBuffer::ThreadSafety::WithoutMutex);
+ // Rewind the reader before the length and deserialize the contents, using
+ // the non-UniquePtr Deserializer.
+ aER = readerBeforeLen;
+ aER.ReadIntoObject(*bufferUPtr);
+ return bufferUPtr;
+ }
+};
+
+} // namespace mozilla
+
+#endif // ProfileChunkedBuffer_h