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/*
*
* Copyright 2015-2016, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <grpc/support/port_platform.h>
#ifdef GPR_POSIX_SOCKET
#include "src/core/iomgr/fd_posix.h"
#include <assert.h>
#include <sys/socket.h>
#include <unistd.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>
#include <grpc/support/useful.h>
#include "src/core/iomgr/pollset_posix.h"
#define CLOSURE_NOT_READY ((grpc_closure *)0)
#define CLOSURE_READY ((grpc_closure *)1)
/* We need to keep a freelist not because of any concerns of malloc performance
* but instead so that implementations with multiple threads in (for example)
* epoll_wait deal with the race between pollset removal and incoming poll
* notifications.
*
* The problem is that the poller ultimately holds a reference to this
* object, so it is very difficult to know when is safe to free it, at least
* without some expensive synchronization.
*
* If we keep the object freelisted, in the worst case losing this race just
* becomes a spurious read notification on a reused fd.
*/
/* TODO(klempner): We could use some form of polling generation count to know
* when these are safe to free. */
/* TODO(klempner): Consider disabling freelisting if we don't have multiple
* threads in poll on the same fd */
/* TODO(klempner): Batch these allocations to reduce fragmentation */
static grpc_fd *fd_freelist = NULL;
static gpr_mu fd_freelist_mu;
static void freelist_fd(grpc_fd *fd) {
gpr_mu_lock(&fd_freelist_mu);
fd->freelist_next = fd_freelist;
fd_freelist = fd;
grpc_iomgr_unregister_object(&fd->iomgr_object);
gpr_mu_unlock(&fd_freelist_mu);
}
static grpc_fd *alloc_fd(int fd) {
grpc_fd *r = NULL;
gpr_mu_lock(&fd_freelist_mu);
if (fd_freelist != NULL) {
r = fd_freelist;
fd_freelist = fd_freelist->freelist_next;
}
gpr_mu_unlock(&fd_freelist_mu);
if (r == NULL) {
r = gpr_malloc(sizeof(grpc_fd));
gpr_mu_init(&r->mu);
}
gpr_mu_lock(&r->mu);
r->shutdown = 0;
r->read_closure = CLOSURE_NOT_READY;
r->write_closure = CLOSURE_NOT_READY;
r->fd = fd;
r->inactive_watcher_root.next = r->inactive_watcher_root.prev =
&r->inactive_watcher_root;
r->freelist_next = NULL;
r->read_watcher = r->write_watcher = NULL;
r->on_done_closure = NULL;
r->closed = 0;
r->released = 0;
gpr_atm_rel_store(&r->refst, 1);
gpr_mu_unlock(&r->mu);
return r;
}
static void destroy(grpc_fd *fd) {
gpr_mu_destroy(&fd->mu);
gpr_free(fd);
}
#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 %d -> %d [%s; %s:%d]", fd->fd, 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);
}
#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 %d -> %d [%s; %s:%d]", fd->fd, 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) {
freelist_fd(fd);
} else {
GPR_ASSERT(old > n);
}
}
void grpc_fd_global_init(void) { gpr_mu_init(&fd_freelist_mu); }
void grpc_fd_global_shutdown(void) {
gpr_mu_lock(&fd_freelist_mu);
gpr_mu_unlock(&fd_freelist_mu);
while (fd_freelist != NULL) {
grpc_fd *fd = fd_freelist;
fd_freelist = fd_freelist->freelist_next;
destroy(fd);
}
gpr_mu_destroy(&fd_freelist_mu);
}
grpc_fd *grpc_fd_create(int fd, const char *name) {
grpc_fd *r = alloc_fd(fd);
char *name2;
gpr_asprintf(&name2, "%s fd=%d", name, fd);
grpc_iomgr_register_object(&r->iomgr_object, name2);
gpr_free(name2);
#ifdef GRPC_FD_REF_COUNT_DEBUG
gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, r, name);
#endif
return r;
}
int grpc_fd_is_orphaned(grpc_fd *fd) {
return (gpr_atm_acq_load(&fd->refst) & 1) == 0;
}
static void pollset_kick_locked(grpc_fd_watcher *watcher) {
gpr_mu_lock(&watcher->pollset->mu);
GPR_ASSERT(watcher->worker);
grpc_pollset_kick_ext(watcher->pollset, watcher->worker,
GRPC_POLLSET_REEVALUATE_POLLING_ON_WAKEUP);
gpr_mu_unlock(&watcher->pollset->mu);
}
static void maybe_wake_one_watcher_locked(grpc_fd *fd) {
if (fd->inactive_watcher_root.next != &fd->inactive_watcher_root) {
pollset_kick_locked(fd->inactive_watcher_root.next);
} else if (fd->read_watcher) {
pollset_kick_locked(fd->read_watcher);
} else if (fd->write_watcher) {
pollset_kick_locked(fd->write_watcher);
}
}
static void wake_all_watchers_locked(grpc_fd *fd) {
grpc_fd_watcher *watcher;
for (watcher = fd->inactive_watcher_root.next;
watcher != &fd->inactive_watcher_root; watcher = watcher->next) {
pollset_kick_locked(watcher);
}
if (fd->read_watcher) {
pollset_kick_locked(fd->read_watcher);
}
if (fd->write_watcher && fd->write_watcher != fd->read_watcher) {
pollset_kick_locked(fd->write_watcher);
}
}
static int has_watchers(grpc_fd *fd) {
return fd->read_watcher != NULL || fd->write_watcher != NULL ||
fd->inactive_watcher_root.next != &fd->inactive_watcher_root;
}
static void close_fd_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
fd->closed = 1;
if (!fd->released) {
close(fd->fd);
} else {
grpc_remove_fd_from_all_epoll_sets(fd->fd);
}
grpc_exec_ctx_enqueue(exec_ctx, fd->on_done_closure, true, NULL);
}
int grpc_fd_wrapped_fd(grpc_fd *fd) {
if (fd->released || fd->closed) {
return -1;
} else {
return fd->fd;
}
}
void grpc_fd_orphan(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure *on_done,
int *release_fd, const char *reason) {
fd->on_done_closure = on_done;
fd->released = release_fd != NULL;
if (!fd->released) {
shutdown(fd->fd, SHUT_RDWR);
} else {
*release_fd = fd->fd;
}
gpr_mu_lock(&fd->mu);
REF_BY(fd, 1, reason); /* remove active status, but keep referenced */
if (!has_watchers(fd)) {
close_fd_locked(exec_ctx, fd);
} else {
wake_all_watchers_locked(fd);
}
gpr_mu_unlock(&fd->mu);
UNREF_BY(fd, 2, reason); /* drop the reference */
}
/* increment refcount by two to avoid changing the orphan bit */
#ifdef GRPC_FD_REF_COUNT_DEBUG
void grpc_fd_ref(grpc_fd *fd, const char *reason, const char *file, int line) {
ref_by(fd, 2, reason, file, line);
}
void grpc_fd_unref(grpc_fd *fd, const char *reason, const char *file,
int line) {
unref_by(fd, 2, reason, file, line);
}
#else
void grpc_fd_ref(grpc_fd *fd) { ref_by(fd, 2); }
void grpc_fd_unref(grpc_fd *fd) { unref_by(fd, 2); }
#endif
static void notify_on_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure **st, grpc_closure *closure) {
if (*st == CLOSURE_NOT_READY) {
/* not ready ==> switch to a waiting state by setting the closure */
*st = closure;
} else if (*st == CLOSURE_READY) {
/* already ready ==> queue the closure to run immediately */
*st = CLOSURE_NOT_READY;
grpc_exec_ctx_enqueue(exec_ctx, closure, !fd->shutdown, NULL);
maybe_wake_one_watcher_locked(fd);
} else {
/* upcallptr was set to a different closure. This is an error! */
gpr_log(GPR_ERROR,
"User called a notify_on function with a previous callback still "
"pending");
abort();
}
}
/* returns 1 if state becomes not ready */
static int set_ready_locked(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure **st) {
if (*st == CLOSURE_READY) {
/* duplicate ready ==> ignore */
return 0;
} else if (*st == CLOSURE_NOT_READY) {
/* not ready, and not waiting ==> flag ready */
*st = CLOSURE_READY;
return 0;
} else {
/* waiting ==> queue closure */
grpc_exec_ctx_enqueue(exec_ctx, *st, !fd->shutdown, NULL);
*st = CLOSURE_NOT_READY;
return 1;
}
}
static void set_ready(grpc_exec_ctx *exec_ctx, grpc_fd *fd, grpc_closure **st) {
/* only one set_ready can be active at once (but there may be a racing
notify_on) */
gpr_mu_lock(&fd->mu);
set_ready_locked(exec_ctx, fd, st);
gpr_mu_unlock(&fd->mu);
}
void grpc_fd_shutdown(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
gpr_mu_lock(&fd->mu);
GPR_ASSERT(!fd->shutdown);
fd->shutdown = 1;
set_ready_locked(exec_ctx, fd, &fd->read_closure);
set_ready_locked(exec_ctx, fd, &fd->write_closure);
gpr_mu_unlock(&fd->mu);
}
void grpc_fd_notify_on_read(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure *closure) {
gpr_mu_lock(&fd->mu);
notify_on_locked(exec_ctx, fd, &fd->read_closure, closure);
gpr_mu_unlock(&fd->mu);
}
void grpc_fd_notify_on_write(grpc_exec_ctx *exec_ctx, grpc_fd *fd,
grpc_closure *closure) {
gpr_mu_lock(&fd->mu);
notify_on_locked(exec_ctx, fd, &fd->write_closure, closure);
gpr_mu_unlock(&fd->mu);
}
uint32_t grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
grpc_pollset_worker *worker, uint32_t read_mask,
uint32_t write_mask, grpc_fd_watcher *watcher) {
uint32_t mask = 0;
grpc_closure *cur;
int requested;
/* keep track of pollers that have requested our events, in case they change
*/
GRPC_FD_REF(fd, "poll");
gpr_mu_lock(&fd->mu);
/* if we are shutdown, then don't add to the watcher set */
if (fd->shutdown) {
watcher->fd = NULL;
watcher->pollset = NULL;
watcher->worker = NULL;
gpr_mu_unlock(&fd->mu);
GRPC_FD_UNREF(fd, "poll");
return 0;
}
/* if there is nobody polling for read, but we need to, then start doing so */
cur = fd->read_closure;
requested = cur != CLOSURE_READY;
if (read_mask && fd->read_watcher == NULL && requested) {
fd->read_watcher = watcher;
mask |= read_mask;
}
/* if there is nobody polling for write, but we need to, then start doing so
*/
cur = fd->write_closure;
requested = cur != CLOSURE_READY;
if (write_mask && fd->write_watcher == NULL && requested) {
fd->write_watcher = watcher;
mask |= write_mask;
}
/* if not polling, remember this watcher in case we need someone to later */
if (mask == 0 && worker != NULL) {
watcher->next = &fd->inactive_watcher_root;
watcher->prev = watcher->next->prev;
watcher->next->prev = watcher->prev->next = watcher;
}
watcher->pollset = pollset;
watcher->worker = worker;
watcher->fd = fd;
gpr_mu_unlock(&fd->mu);
return mask;
}
void grpc_fd_end_poll(grpc_exec_ctx *exec_ctx, grpc_fd_watcher *watcher,
int got_read, int got_write) {
int was_polling = 0;
int kick = 0;
grpc_fd *fd = watcher->fd;
if (fd == NULL) {
return;
}
gpr_mu_lock(&fd->mu);
if (watcher == fd->read_watcher) {
/* remove read watcher, kick if we still need a read */
was_polling = 1;
if (!got_read) {
kick = 1;
}
fd->read_watcher = NULL;
}
if (watcher == fd->write_watcher) {
/* remove write watcher, kick if we still need a write */
was_polling = 1;
if (!got_write) {
kick = 1;
}
fd->write_watcher = NULL;
}
if (!was_polling && watcher->worker != NULL) {
/* remove from inactive list */
watcher->next->prev = watcher->prev;
watcher->prev->next = watcher->next;
}
if (got_read) {
if (set_ready_locked(exec_ctx, fd, &fd->read_closure)) {
kick = 1;
}
}
if (got_write) {
if (set_ready_locked(exec_ctx, fd, &fd->write_closure)) {
kick = 1;
}
}
if (kick) {
maybe_wake_one_watcher_locked(fd);
}
if (grpc_fd_is_orphaned(fd) && !has_watchers(fd) && !fd->closed) {
close_fd_locked(exec_ctx, fd);
}
gpr_mu_unlock(&fd->mu);
GRPC_FD_UNREF(fd, "poll");
}
void grpc_fd_become_readable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
set_ready(exec_ctx, fd, &fd->read_closure);
}
void grpc_fd_become_writable(grpc_exec_ctx *exec_ctx, grpc_fd *fd) {
set_ready(exec_ctx, fd, &fd->write_closure);
}
#endif
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