From 8ed56f5a4b63157c98d579bca114ac355357fc82 Mon Sep 17 00:00:00 2001 From: Sree Kuchibhotla Date: Wed, 3 May 2017 09:59:25 -0700 Subject: [PATCH] Remove refcnt from fd --- .../lib/iomgr/ev_epoll_thread_pool_linux.c | 112 ++++++------------ 1 file changed, 35 insertions(+), 77 deletions(-) diff --git a/src/core/lib/iomgr/ev_epoll_thread_pool_linux.c b/src/core/lib/iomgr/ev_epoll_thread_pool_linux.c index 055b31331d5..96e8000da4e 100644 --- a/src/core/lib/iomgr/ev_epoll_thread_pool_linux.c +++ b/src/core/lib/iomgr/ev_epoll_thread_pool_linux.c @@ -72,6 +72,11 @@ static int grpc_polling_trace = 0; /* Disabled by default */ gpr_log(GPR_INFO, (fmt), __VA_ARGS__); \ } +/* The alarm system needs to be able to wakeup 'some poller' sometimes + * (specifically when a new alarm needs to be triggered earlier than the next + * alarm 'epoch'). This wakeup_fd gives us something to alert on when such a + * case occurs. */ + /* TODO: sreek: Right now, this wakes up all pollers. In future we should make * sure to wake up one polling thread (which can wake up other threads if * needed) */ @@ -87,15 +92,9 @@ struct grpc_fd { struct polling_island *pi; int fd; - /* refst format: - bit 0 : 1=Active / 0=Orphaned - bits 1-n : refcount - Ref/Unref by two to avoid altering the orphaned bit */ - gpr_atm refst; - - /* The fd is either closed or we relinquished control of it. In either - cases, this indicates that the 'fd' on this structure is no longer - valid */ + + /* The fd is either closed or we relinquished control of it. In either cases, + this indicates that the 'fd' on this structure is no longer valid */ bool orphaned; gpr_atm read_closure; @@ -182,9 +181,7 @@ struct grpc_pollset { /******************************************************************************* * Pollset-set Declarations */ -struct grpc_pollset_set { - void *no_op; -}; +struct grpc_pollset_set {}; /***************************************************************************** * Dedicated polling threads and pollsets - Declarations @@ -521,57 +518,31 @@ static void polling_island_global_shutdown() { * becomes a spurious read notification on a reused fd. */ -/* The alarm system needs to be able to wakeup 'some poller' sometimes - * (specifically when a new alarm needs to be triggered earlier than the next - * alarm 'epoch'). This wakeup_fd gives us something to alert on when such a - * case occurs. */ - static grpc_fd *fd_freelist = NULL; static gpr_mu fd_freelist_mu; -// #define GRPC_FD_REF_COUNT_DEBUG -#ifdef GRPC_FD_REF_COUNT_DEBUG -#define REF_BY(fd, n, reason) ref_by(fd, n, reason, __FILE__, __LINE__) -#define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__) -static void ref_by(grpc_fd *fd, int n, const char *reason, const char *file, - int line) { - gpr_log(GPR_DEBUG, "FD %d %p ref %d %ld -> %ld [%s; %s:%d]", fd->fd, - (void *)fd, n, gpr_atm_no_barrier_load(&fd->refst), - gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line); -#else -#define REF_BY(fd, n, reason) ref_by(fd, n) -#define UNREF_BY(fd, n, reason) unref_by(fd, n) -static void ref_by(grpc_fd *fd, int n) { -#endif - GPR_ASSERT(gpr_atm_no_barrier_fetch_add(&fd->refst, n) > 0); -} +static grpc_fd *get_fd_from_freelist() { + grpc_fd *new_fd = NULL; -#ifdef GRPC_FD_REF_COUNT_DEBUG -static void unref_by(grpc_fd *fd, int n, const char *reason, const char *file, - int line) { - gpr_atm old; - gpr_log(GPR_DEBUG, "FD %d %p unref %d %ld -> %ld [%s; %s:%d]", fd->fd, - (void *)fd, n, gpr_atm_no_barrier_load(&fd->refst), - gpr_atm_no_barrier_load(&fd->refst) - n, reason, file, line); -#else -static void unref_by(grpc_fd *fd, int n) { - gpr_atm old; -#endif - old = gpr_atm_full_fetch_add(&fd->refst, -n); - if (old == n) { - /* Add the fd to the freelist */ - gpr_mu_lock(&fd_freelist_mu); - fd->freelist_next = fd_freelist; - fd_freelist = fd; - grpc_iomgr_unregister_object(&fd->iomgr_object); - - grpc_lfev_destroy(&fd->read_closure); - grpc_lfev_destroy(&fd->write_closure); - - gpr_mu_unlock(&fd_freelist_mu); - } else { - GPR_ASSERT(old > n); + gpr_mu_lock(&fd_freelist_mu); + if (fd_freelist != NULL) { + new_fd = fd_freelist; + fd_freelist = fd_freelist->freelist_next; } + gpr_mu_unlock(&fd_freelist_mu); + return new_fd; +} + +static void add_fd_to_freelist(grpc_fd *fd) { + gpr_mu_lock(&fd_freelist_mu); + fd->freelist_next = fd_freelist; + fd_freelist = fd; + grpc_iomgr_unregister_object(&fd->iomgr_object); + + grpc_lfev_destroy(&fd->read_closure); + grpc_lfev_destroy(&fd->write_closure); + + gpr_mu_unlock(&fd_freelist_mu); } static void fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); } @@ -589,15 +560,7 @@ static void fd_global_shutdown(void) { } static grpc_fd *fd_create(int fd, const char *name) { - grpc_fd *new_fd = NULL; - - gpr_mu_lock(&fd_freelist_mu); - if (fd_freelist != NULL) { - new_fd = fd_freelist; - fd_freelist = fd_freelist->freelist_next; - } - gpr_mu_unlock(&fd_freelist_mu); - + grpc_fd *new_fd = get_fd_from_freelist(); if (new_fd == NULL) { new_fd = gpr_malloc(sizeof(grpc_fd)); gpr_mu_init(&new_fd->mu); @@ -609,7 +572,6 @@ static grpc_fd *fd_create(int fd, const char *name) { gpr_mu_lock(&new_fd->mu); new_fd->pi = NULL; - gpr_atm_rel_store(&new_fd->refst, (gpr_atm)1); new_fd->fd = fd; new_fd->orphaned = false; grpc_lfev_init(&new_fd->read_closure); @@ -623,9 +585,7 @@ static grpc_fd *fd_create(int fd, const char *name) { char *fd_name; gpr_asprintf(&fd_name, "%s fd=%d", name, fd); grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name); -#ifdef GRPC_FD_REF_COUNT_DEBUG gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, (void *)new_fd, fd_name); -#endif gpr_free(fd_name); /* Associate the fd with one of the dedicated pi */ @@ -665,14 +625,9 @@ static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, fd->orphaned = true; - /* Remove the active status but keep referenced. We want this grpc_fd struct - to be alive (and not added to freelist) until the end of this function */ - REF_BY(fd, 1, reason); - /* Remove the fd from the polling island */ if (fd->pi != NULL) { - polling_island *pi = fd->pi; - polling_island_remove_fd(pi, fd, is_fd_closed, &error); + polling_island_remove_fd(fd->pi, fd, is_fd_closed, &error); unref_pi = fd->pi; fd->pi = NULL; } @@ -680,7 +635,10 @@ static void fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure_sched(exec_ctx, fd->on_done_closure, GRPC_ERROR_REF(error)); gpr_mu_unlock(&fd->mu); - UNREF_BY(fd, 2, reason); /* Drop the reference */ + + /* We are done with this fd. Release it (i.e add back to freelist) */ + add_fd_to_freelist(fd); + if (unref_pi != NULL) { /* Unref stale polling island here, outside the fd lock above. The polling island owns a workqueue which owns an fd, and unreffing