Add shim to support condition variable wakeup fds where pipe/eventfd is not available

5 files changed, 407 insertions, 4 deletions

diff --git a/src/core/lib/iomgr/wakeup_fd_cv.c b/src/core/lib/iomgr/wakeup_fd_cv.c
new file mode 100644
index 0000000000..bfdc2cb422
--- /dev/null
+++ b/src/core/lib/iomgr/wakeup_fd_cv.c
@@ -0,0 +1,328 @@
+/*
+ *
+ * Copyright 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_WAKEUP_FD
+
+#include "src/core/lib/iomgr/wakeup_fd_posix.h"
+
+#include <errno.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+#include <grpc/support/thd.h>
+#include <grpc/support/time.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/lib/iomgr/ev_posix.h"
+
+#define MAX_TABLE_RESIZE 256
+#define DEFAULT_TABLE_SIZE 16
+#define POLL_PERIOD_MS 1000
+
+#define FD_TO_IDX(fd) (-(fd)-1)
+#define IDX_TO_FD(idx) (-(idx)-1)
+
+typedef struct cv_node {
+  gpr_cv* cv;
+  struct cv_node* next;
+} cv_node;
+
+typedef struct fd_node {
+  int is_set;
+  cv_node* cvs;
+  struct fd_node* next_free;
+} fd_node;
+
+typedef struct cv_fd_table {
+  fd_node* cvfds;
+  fd_node* free_fds;
+  unsigned int size;
+  grpc_poll_function_type poll;
+} cv_fd_table;
+
+typedef struct poll_result {
+  struct pollfd* fds;
+  gpr_cv* cv;
+  int completed;
+  int res;
+  int err;
+} poll_result;
+
+typedef struct poll_args {
+  struct pollfd* fds;
+  nfds_t nfds;
+  int timeout;
+  poll_result* result;
+} poll_args;
+
+static gpr_mu g_mu = PTHREAD_MUTEX_INITIALIZER;
+static cv_fd_table g_cvfds;
+
+// Some environments do not implement pthread_cancel(), so we run
+// this poll in a detached thread, and wake up periodically and
+// check if the calling thread is still waiting on a result
+static void run_poll(void* arg) {
+  int result, timeout;
+  poll_args* pargs = (poll_args*)arg;
+  gpr_mu_lock(&g_mu);
+  if (pargs->result != NULL) {
+    while (pargs->result != NULL) {
+      if (pargs->timeout < 0) {
+        timeout = POLL_PERIOD_MS;
+      } else {
+        timeout = GPR_MIN(POLL_PERIOD_MS, pargs->timeout);
+        pargs->timeout -= timeout;
+      }
+      gpr_mu_unlock(&g_mu);
+      result = g_cvfds.poll(pargs->fds, pargs->nfds, timeout);
+      gpr_mu_lock(&g_mu);
+      if (pargs->result != NULL) {
+        if (result != 0 || pargs->timeout == 0) {
+          memcpy(pargs->result->fds, pargs->fds,
+                 sizeof(struct pollfd) * pargs->nfds);
+          pargs->result->res = result;
+          pargs->result->err = errno;
+          pargs->result->completed = 1;
+          gpr_cv_signal(pargs->result->cv);
+          break;
+        }
+      }
+    }
+  }
+  gpr_free(pargs->fds);
+  gpr_free(pargs);
+  gpr_mu_unlock(&g_mu);
+}
+
+int cvfd_poll(struct pollfd* fds, nfds_t nfds, int timeout) {
+  unsigned int i;
+  int res, idx;
+  cv_node *cvn, *prev;
+  struct pollfd* sockfds;
+  nfds_t nsockfds = 0;
+  gpr_cv pollcv;
+  gpr_thd_id t_id;
+  gpr_thd_options opt;
+  poll_args* pargs;
+  poll_result* pres;
+  gpr_mu_lock(&g_mu);
+  gpr_cv_init(&pollcv);
+  for (i = 0; i < nfds; i++) {
+    fds[i].revents = 0;
+    if (fds[i].fd < 0 && (fds[i].events & POLLIN)) {
+      idx = FD_TO_IDX(fds[i].fd);
+      cvn = gpr_malloc(sizeof(cv_node));
+      cvn->cv = &pollcv;
+      cvn->next = g_cvfds.cvfds[idx].cvs;
+      g_cvfds.cvfds[idx].cvs = cvn;
+      // We should return immediately if there are pending events,
+      // but we still need to call poll() to check for socket events
+      if (g_cvfds.cvfds[idx].is_set) {
+        timeout = 0;
+      }
+    } else if (fds[i].fd >= 0) {
+      nsockfds++;
+    }
+  }
+  sockfds = gpr_malloc(sizeof(struct pollfd) * nsockfds);
+  idx = 0;
+  for (i = 0; i < nfds; i++) {
+    if (fds[i].fd >= 0) {
+      sockfds[idx].fd = fds[i].fd;
+      sockfds[idx].events = fds[i].events;
+      sockfds[idx].revents = 0;
+      idx++;
+    }
+  }
+
+  errno = 0;
+  if (nsockfds > 0) {
+    pres = gpr_malloc(sizeof(struct poll_result));
+    pargs = gpr_malloc(sizeof(struct poll_args));
+
+    pargs->fds = gpr_malloc(sizeof(struct pollfd) * nsockfds);
+    memcpy(pargs->fds, sockfds, sizeof(struct pollfd) * nsockfds);
+    pargs->nfds = nsockfds;
+    pargs->timeout = timeout;
+    pargs->result = pres;
+
+    pres->fds = sockfds;
+    pres->cv = &pollcv;
+    pres->completed = 0;
+    pres->res = 0;
+    pres->err = 0;
+
+    opt = gpr_thd_options_default();
+    gpr_thd_options_set_detached(&opt);
+    gpr_thd_new(&t_id, &run_poll, pargs, &opt);
+    // We want the poll() thread to trigger the deadline, so wait forever here
+    gpr_cv_wait(&pollcv, &g_mu, gpr_inf_future(GPR_CLOCK_MONOTONIC));
+    if (!pres->completed) {
+      pargs->result = NULL;
+    }
+    res = pres->res;
+    errno = pres->err;
+    gpr_free(pres);
+  } else {
+    gpr_timespec deadline = gpr_now(GPR_CLOCK_REALTIME);
+    deadline =
+        gpr_time_add(deadline, gpr_time_from_millis(timeout, GPR_TIMESPAN));
+    gpr_cv_wait(&pollcv, &g_mu, deadline);
+    res = 0;
+  }
+  idx = 0;
+  for (i = 0; i < nfds; i++) {
+    if (fds[i].fd < 0 && (fds[i].events & POLLIN)) {
+      cvn = g_cvfds.cvfds[FD_TO_IDX(fds[i].fd)].cvs;
+      prev = NULL;
+      while (cvn->cv != &pollcv) {
+        prev = cvn;
+        cvn = cvn->next;
+        GPR_ASSERT(cvn);
+      }
+      if (!prev) {
+        g_cvfds.cvfds[FD_TO_IDX(fds[i].fd)].cvs = cvn->next;
+      } else {
+        prev->next = cvn->next;
+      }
+      gpr_free(cvn);
+
+      if (g_cvfds.cvfds[FD_TO_IDX(fds[i].fd)].is_set) {
+        fds[i].revents = POLLIN;
+        if (res >= 0) res++;
+      }
+    } else if (fds[i].fd >= 0) {
+      fds[i].revents = sockfds[idx].revents;
+      idx++;
+    }
+  }
+  gpr_free(sockfds);
+  gpr_cv_destroy(&pollcv);
+  gpr_mu_unlock(&g_mu);
+
+  return res;
+}
+
+static grpc_error* cv_fd_init(grpc_wakeup_fd* fd_info) {
+  unsigned int i, newsize;
+  int idx;
+  gpr_mu_lock(&g_mu);
+  if (!g_cvfds.free_fds) {
+    newsize = GPR_MIN(g_cvfds.size * 2, g_cvfds.size + MAX_TABLE_RESIZE);
+    g_cvfds.cvfds = gpr_realloc(g_cvfds.cvfds, sizeof(fd_node) * newsize);
+    for (i = g_cvfds.size; i < newsize; i++) {
+      g_cvfds.cvfds[i].is_set = 0;
+      g_cvfds.cvfds[i].cvs = NULL;
+      g_cvfds.cvfds[i].next_free = g_cvfds.free_fds;
+      g_cvfds.free_fds = &g_cvfds.cvfds[i];
+    }
+    g_cvfds.size = newsize;
+  }
+
+  idx = (int)(g_cvfds.free_fds - g_cvfds.cvfds);
+  g_cvfds.free_fds = g_cvfds.free_fds->next_free;
+  g_cvfds.cvfds[idx].cvs = NULL;
+  g_cvfds.cvfds[idx].is_set = 0;
+  fd_info->read_fd = IDX_TO_FD(idx);
+  fd_info->write_fd = -1;
+  gpr_mu_unlock(&g_mu);
+  return GRPC_ERROR_NONE;
+}
+
+void grpc_global_cv_fd_table_init() {
+  gpr_mu_lock(&g_mu);
+  g_cvfds.size = DEFAULT_TABLE_SIZE;
+  g_cvfds.cvfds = gpr_malloc(sizeof(fd_node) * DEFAULT_TABLE_SIZE);
+  g_cvfds.free_fds = NULL;
+  for (int i = 0; i < DEFAULT_TABLE_SIZE; i++) {
+    g_cvfds.cvfds[i].is_set = 0;
+    g_cvfds.cvfds[i].cvs = NULL;
+    g_cvfds.cvfds[i].next_free = g_cvfds.free_fds;
+    g_cvfds.free_fds = &g_cvfds.cvfds[i];
+  }
+  // Override the poll function with one that supports cvfds
+  g_cvfds.poll = grpc_poll_function;
+  grpc_poll_function = &cvfd_poll;
+  gpr_mu_unlock(&g_mu);
+}
+
+void grpc_global_cv_fd_table_shutdown() {
+  gpr_mu_lock(&g_mu);
+  grpc_poll_function = g_cvfds.poll;
+  gpr_free(g_cvfds.cvfds);
+  gpr_mu_unlock(&g_mu);
+}
+
+static grpc_error* cv_fd_wakeup(grpc_wakeup_fd* fd_info) {
+  cv_node* cvn;
+  gpr_mu_lock(&g_mu);
+  g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].is_set = 1;
+  cvn = g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].cvs;
+  while (cvn) {
+    gpr_cv_signal(cvn->cv);
+    cvn = cvn->next;
+  }
+  gpr_mu_unlock(&g_mu);
+  return GRPC_ERROR_NONE;
+}
+
+static grpc_error* cv_fd_consume(grpc_wakeup_fd* fd_info) {
+  gpr_mu_lock(&g_mu);
+  g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].is_set = 0;
+  gpr_mu_unlock(&g_mu);
+  return GRPC_ERROR_NONE;
+}
+
+static void cv_fd_destroy(grpc_wakeup_fd* fd_info) {
+  if (fd_info->read_fd == 0) {
+    return;
+  }
+  gpr_mu_lock(&g_mu);
+  // Assert that there are no active pollers
+  GPR_ASSERT(!g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].cvs);
+  g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)].next_free = g_cvfds.free_fds;
+  g_cvfds.free_fds = &g_cvfds.cvfds[FD_TO_IDX(fd_info->read_fd)];
+  gpr_mu_unlock(&g_mu);
+}
+
+static int cv_check_availability(void) { return 1; }
+
+const grpc_wakeup_fd_vtable grpc_cv_wakeup_fd_vtable = {
+    cv_fd_init, cv_fd_consume, cv_fd_wakeup, cv_fd_destroy,
+    cv_check_availability};
+
+#endif /* GPR_POSIX_WAKUP_FD */
diff --git a/src/core/lib/iomgr/wakeup_fd_cv.h b/src/core/lib/iomgr/wakeup_fd_cv.h
new file mode 100644
index 0000000000..22ee6c0bbe
--- /dev/null
+++ b/src/core/lib/iomgr/wakeup_fd_cv.h
@@ -0,0 +1,58 @@
+/*
+ *
+ * Copyright 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.
+ *
+ */
+
+/*
+ * wakeup_fd_cv uses condition variables to implement wakeup fds.
+ *
+ * It is intended for use only in cases when eventfd() and pipe() are not
+ * available.  It can only be used with the "poll" engine.
+ *
+ * Implementation:
+ * A global table of cv wakeup fds is mantained.  A cv wakeup fd is a negative
+ * file descriptor.  poll() is then run in a background thread with only the
+ * real socket fds while we wait on a condition variable trigged by either the
+ * poll() called or a wakeup_fd() call.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_IOMGR_WAKEUP_FD_CV_H
+#define GRPC_CORE_LIB_IOMGR_WAKEUP_FD_CV_H
+
+#include "src/core/lib/iomgr/wakeup_fd_posix.h"
+
+void grpc_global_cv_fd_table_init();
+void grpc_global_cv_fd_table_shutdown();
+
+extern grpc_wakeup_fd_vtable grpc_cv_wakeup_fd_vtable;
+
+#endif /* GRPC_CORE_LIB_IOMGR_WAKEUP_FD_CV_H */
diff --git a/src/core/lib/iomgr/wakeup_fd_pipe.c b/src/core/lib/iomgr/wakeup_fd_pipe.c
index 4e5dbdcb73..3dc94c94ba 100644
--- a/src/core/lib/iomgr/wakeup_fd_pipe.c
+++ b/src/core/lib/iomgr/wakeup_fd_pipe.c
@@ -95,8 +95,13 @@ static void pipe_destroy(grpc_wakeup_fd* fd_info) {
 }
 
 static int pipe_check_availability(void) {
-  /* Assume that pipes are always available. */
-  return 1;
+  grpc_wakeup_fd fd;
+  if (pipe_init(&fd) == GRPC_ERROR_NONE) {
+    pipe_destroy(&fd);
+    return 1;
+  } else {
+    return 0;
+  }
 }
 
 const grpc_wakeup_fd_vtable grpc_pipe_wakeup_fd_vtable = {
diff --git a/src/core/lib/iomgr/wakeup_fd_posix.c b/src/core/lib/iomgr/wakeup_fd_posix.c
index 046208abc8..564b836154 100644
--- a/src/core/lib/iomgr/wakeup_fd_posix.c
+++ b/src/core/lib/iomgr/wakeup_fd_posix.c
@@ -36,22 +36,33 @@
 #ifdef GPR_POSIX_WAKEUP_FD
 
 #include <stddef.h>
+#include "src/core/lib/iomgr/wakeup_fd_cv.h"
 #include "src/core/lib/iomgr/wakeup_fd_pipe.h"
 #include "src/core/lib/iomgr/wakeup_fd_posix.h"
 
 static const grpc_wakeup_fd_vtable *wakeup_fd_vtable = NULL;
 int grpc_allow_specialized_wakeup_fd = 1;
+int grpc_allow_pipe_wakeup_fd = 1;
 
 void grpc_wakeup_fd_global_init(void) {
   if (grpc_allow_specialized_wakeup_fd &&
       grpc_specialized_wakeup_fd_vtable.check_availability()) {
     wakeup_fd_vtable = &grpc_specialized_wakeup_fd_vtable;
-  } else {
+  } else if (grpc_allow_pipe_wakeup_fd &&
+             grpc_pipe_wakeup_fd_vtable.check_availability()) {
     wakeup_fd_vtable = &grpc_pipe_wakeup_fd_vtable;
+  } else {
+    wakeup_fd_vtable = &grpc_cv_wakeup_fd_vtable;
+    grpc_global_cv_fd_table_init();
   }
 }
 
-void grpc_wakeup_fd_global_destroy(void) { wakeup_fd_vtable = NULL; }
+void grpc_wakeup_fd_global_destroy(void) {
+  if (wakeup_fd_vtable == &grpc_cv_wakeup_fd_vtable) {
+    grpc_global_cv_fd_table_shutdown();
+  }
+  wakeup_fd_vtable = NULL;
+}
 
 grpc_error *grpc_wakeup_fd_init(grpc_wakeup_fd *fd_info) {
   return wakeup_fd_vtable->init(fd_info);
diff --git a/src/core/lib/iomgr/wakeup_fd_posix.h b/src/core/lib/iomgr/wakeup_fd_posix.h
index e269f242d8..a9f902bc9f 100644
--- a/src/core/lib/iomgr/wakeup_fd_posix.h
+++ b/src/core/lib/iomgr/wakeup_fd_posix.h
@@ -88,6 +88,7 @@ struct grpc_wakeup_fd {
 };
 
 extern int grpc_allow_specialized_wakeup_fd;
+extern int grpc_allow_pipe_wakeup_fd;
 
 #define GRPC_WAKEUP_FD_GET_READ_FD(fd_info) ((fd_info)->read_fd)