diff options
Diffstat (limited to 'include/haproxy/ring-t.h')
| -rw-r--r-- | include/haproxy/ring-t.h | 59 |
1 files changed, 55 insertions, 4 deletions
diff --git a/include/haproxy/ring-t.h b/include/haproxy/ring-t.h index b89c886..4e091ee 100644 --- a/include/haproxy/ring-t.h +++ b/include/haproxy/ring-t.h @@ -27,7 +27,7 @@ #include <haproxy/thread.h> /* The code below handles circular buffers with single-producer and multiple - * readers (up to 255). The buffer storage area must remain always allocated. + * readers (up to 254). The buffer storage area must remain always allocated. * It's made of series of payload blocks followed by a readers count (RC). * There is always a readers count at the beginning of the buffer as well. Each * payload block is composed of a varint-encoded size (VI) followed by the @@ -96,11 +96,62 @@ #define RING_WF_WAIT_MODE 0x00000001 /* wait for new contents */ #define RING_WF_SEEK_NEW 0x00000002 /* seek to new contents */ +/* ring flags */ +#define RING_FL_MAPPED 0x00000001 /* mmapped area, must not free() */ + +/* keep values below in decimal, they may be dumped in error messages */ +#define RING_WRITING_SIZE 255 /* the next message's size is being written */ +#define RING_MAX_READERS 254 /* highest supported value for RC */ + +/* mask used to lock the tail */ +#define RING_TAIL_LOCK (1ULL << ((sizeof(size_t) * 8) - 1)) + +/* A cell describing a waiting thread. + * ->next is initialized to 0x1 before the pointer is set, so that any + * leader thread can see that the pointer is not set yet. This allows + * to enqueue all waiting threads very quickly using XCHG() on the head + * without having to rely on a flaky CAS, while threads finish their setup + * in parallel. The pointer will turn to NULL again once the thread is + * released. + */ +struct ring_wait_cell { + size_t to_send_self; // size needed to serialize this msg + size_t needed_tot; // size needed to serialize pending msgs + size_t maxlen; // msg truncated to this size + const struct ist *pfx; // prefixes + size_t npfx; // #prefixes + const struct ist *msg; // message parts + size_t nmsg; // #message parts + struct ring_wait_cell *next; // next waiting thread +}; + +/* this is the mmapped part */ +struct ring_storage { + size_t size; // storage size + size_t rsvd; // header length (used for file-backed maps) + THREAD_PAD(64 - 2 * sizeof(size_t)); + size_t tail; // storage tail + THREAD_PAD(64 - sizeof(size_t)); + size_t head; // storage head + THREAD_PAD(64 - sizeof(size_t)); + char area[0]; // storage area begins immediately here +}; + +/* this is the ring definition, config, waiters etc */ struct ring { - struct buffer buf; // storage area - struct list waiters; // list of waiters, for now, CLI "show event" - __decl_thread(HA_RWLOCK_T lock); + struct ring_storage *storage; // the mapped part + struct mt_list waiters; // list of waiters, for now, CLI "show event" int readers_count; + uint flags; // RING_FL_* + uint pending; // new writes that have not yet been subject to a wakeup + uint waking; // indicates a thread is currently waking up readers + + /* keep the queue in a separate cache line below */ + THREAD_PAD(64 - 3*sizeof(void*) - 4*sizeof(int)); + struct { + struct ring_wait_cell *ptr; + THREAD_PAD(64 - sizeof(void*)); + } queue[RING_WAIT_QUEUES + 1]; // wait queue + 1 spacer }; #endif /* _HAPROXY_RING_T_H */ |