Merge pull request #15780 from apolcyn/cares_windows_build

Separate out the posix part of the c-ares driver

1 files changed, 311 insertions, 0 deletions

diff --git a/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
new file mode 100644
index 0000000000..06a6e853f5
--- /dev/null
+++ b/src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc
@@ -0,0 +1,311 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/iomgr/port.h"
+#if GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER)
+
+#include <ares.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h"
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/time.h>
+#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/iomgr/ev_posix.h"
+#include "src/core/lib/iomgr/iomgr_internal.h"
+#include "src/core/lib/iomgr/sockaddr_utils.h"
+
+typedef struct fd_node {
+  /** the owner of this fd node */
+  grpc_ares_ev_driver* ev_driver;
+  /** a closure wrapping on_readable_locked, which should be
+     invoked when the grpc_fd in this node becomes readable. */
+  grpc_closure read_closure;
+  /** a closure wrapping on_writable_locked, which should be
+     invoked when the grpc_fd in this node becomes writable. */
+  grpc_closure write_closure;
+  /** next fd node in the list */
+  struct fd_node* next;
+
+  /** wrapped fd that's polled by grpc's poller for the current platform */
+  grpc_core::GrpcPolledFd* grpc_polled_fd;
+  /** if the readable closure has been registered */
+  bool readable_registered;
+  /** if the writable closure has been registered */
+  bool writable_registered;
+  /** if the fd has been shutdown yet from grpc iomgr perspective */
+  bool already_shutdown;
+} fd_node;
+
+struct grpc_ares_ev_driver {
+  /** the ares_channel owned by this event driver */
+  ares_channel channel;
+  /** pollset set for driving the IO events of the channel */
+  grpc_pollset_set* pollset_set;
+  /** refcount of the event driver */
+  gpr_refcount refs;
+
+  /** combiner to synchronize c-ares and I/O callbacks on */
+  grpc_combiner* combiner;
+  /** a list of grpc_fd that this event driver is currently using. */
+  fd_node* fds;
+  /** is this event driver currently working? */
+  bool working;
+  /** is this event driver being shut down */
+  bool shutting_down;
+};
+
+static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver);
+
+static grpc_ares_ev_driver* grpc_ares_ev_driver_ref(
+    grpc_ares_ev_driver* ev_driver) {
+  gpr_log(GPR_DEBUG, "Ref ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
+  gpr_ref(&ev_driver->refs);
+  return ev_driver;
+}
+
+static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver* ev_driver) {
+  gpr_log(GPR_DEBUG, "Unref ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
+  if (gpr_unref(&ev_driver->refs)) {
+    gpr_log(GPR_DEBUG, "destroy ev_driver %" PRIuPTR, (uintptr_t)ev_driver);
+    GPR_ASSERT(ev_driver->fds == nullptr);
+    GRPC_COMBINER_UNREF(ev_driver->combiner, "free ares event driver");
+    ares_destroy(ev_driver->channel);
+    gpr_free(ev_driver);
+  }
+}
+
+static void fd_node_destroy_locked(fd_node* fdn) {
+  gpr_log(GPR_DEBUG, "delete fd: %s", fdn->grpc_polled_fd->GetName());
+  GPR_ASSERT(!fdn->readable_registered);
+  GPR_ASSERT(!fdn->writable_registered);
+  GPR_ASSERT(fdn->already_shutdown);
+  grpc_core::Delete(fdn->grpc_polled_fd);
+  gpr_free(fdn);
+}
+
+static void fd_node_shutdown_locked(fd_node* fdn, const char* reason) {
+  if (!fdn->already_shutdown) {
+    fdn->already_shutdown = true;
+    fdn->grpc_polled_fd->ShutdownLocked(
+        GRPC_ERROR_CREATE_FROM_STATIC_STRING(reason));
+  }
+}
+
+grpc_error* grpc_ares_ev_driver_create_locked(grpc_ares_ev_driver** ev_driver,
+                                              grpc_pollset_set* pollset_set,
+                                              grpc_combiner* combiner) {
+  *ev_driver = static_cast<grpc_ares_ev_driver*>(
+      gpr_malloc(sizeof(grpc_ares_ev_driver)));
+  ares_options opts;
+  memset(&opts, 0, sizeof(opts));
+  opts.flags |= ARES_FLAG_STAYOPEN;
+  int status = ares_init_options(&(*ev_driver)->channel, &opts, ARES_OPT_FLAGS);
+  grpc_core::ConfigureAresChannelLocked(&(*ev_driver)->channel);
+  gpr_log(GPR_DEBUG, "grpc_ares_ev_driver_create_locked");
+  if (status != ARES_SUCCESS) {
+    char* err_msg;
+    gpr_asprintf(&err_msg, "Failed to init ares channel. C-ares error: %s",
+                 ares_strerror(status));
+    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_msg);
+    gpr_free(err_msg);
+    gpr_free(*ev_driver);
+    return err;
+  }
+  (*ev_driver)->combiner = GRPC_COMBINER_REF(combiner, "ares event driver");
+  gpr_ref_init(&(*ev_driver)->refs, 1);
+  (*ev_driver)->pollset_set = pollset_set;
+  (*ev_driver)->fds = nullptr;
+  (*ev_driver)->working = false;
+  (*ev_driver)->shutting_down = false;
+  return GRPC_ERROR_NONE;
+}
+
+void grpc_ares_ev_driver_destroy_locked(grpc_ares_ev_driver* ev_driver) {
+  // We mark the event driver as being shut down. If the event driver
+  // is working, grpc_ares_notify_on_event_locked will shut down the
+  // fds; if it's not working, there are no fds to shut down.
+  ev_driver->shutting_down = true;
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver) {
+  ev_driver->shutting_down = true;
+  fd_node* fn = ev_driver->fds;
+  while (fn != nullptr) {
+    fd_node_shutdown_locked(fn, "grpc_ares_ev_driver_shutdown");
+    fn = fn->next;
+  }
+}
+
+// Search fd in the fd_node list head. This is an O(n) search, the max possible
+// value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests.
+static fd_node* pop_fd_node_locked(fd_node** head, ares_socket_t as) {
+  fd_node dummy_head;
+  dummy_head.next = *head;
+  fd_node* node = &dummy_head;
+  while (node->next != nullptr) {
+    if (node->next->grpc_polled_fd->GetWrappedAresSocketLocked() == as) {
+      fd_node* ret = node->next;
+      node->next = node->next->next;
+      *head = dummy_head.next;
+      return ret;
+    }
+    node = node->next;
+  }
+  return nullptr;
+}
+
+static void on_readable_locked(void* arg, grpc_error* error) {
+  fd_node* fdn = static_cast<fd_node*>(arg);
+  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
+  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+  fdn->readable_registered = false;
+  gpr_log(GPR_DEBUG, "readable on %s", fdn->grpc_polled_fd->GetName());
+  if (error == GRPC_ERROR_NONE) {
+    do {
+      ares_process_fd(ev_driver->channel, as, ARES_SOCKET_BAD);
+    } while (fdn->grpc_polled_fd->IsFdStillReadableLocked());
+  } else {
+    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
+    // timed out. The pending lookups made on this ev_driver will be cancelled
+    // by the following ares_cancel() and the on_done callbacks will be invoked
+    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
+    // ev_driver will be cleaned up in the follwing
+    // grpc_ares_notify_on_event_locked().
+    ares_cancel(ev_driver->channel);
+  }
+  grpc_ares_notify_on_event_locked(ev_driver);
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+static void on_writable_locked(void* arg, grpc_error* error) {
+  fd_node* fdn = static_cast<fd_node*>(arg);
+  grpc_ares_ev_driver* ev_driver = fdn->ev_driver;
+  const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked();
+  fdn->writable_registered = false;
+  gpr_log(GPR_DEBUG, "writable on %s", fdn->grpc_polled_fd->GetName());
+  if (error == GRPC_ERROR_NONE) {
+    ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, as);
+  } else {
+    // If error is not GRPC_ERROR_NONE, it means the fd has been shutdown or
+    // timed out. The pending lookups made on this ev_driver will be cancelled
+    // by the following ares_cancel() and the on_done callbacks will be invoked
+    // with a status of ARES_ECANCELLED. The remaining file descriptors in this
+    // ev_driver will be cleaned up in the follwing
+    // grpc_ares_notify_on_event_locked().
+    ares_cancel(ev_driver->channel);
+  }
+  grpc_ares_notify_on_event_locked(ev_driver);
+  grpc_ares_ev_driver_unref(ev_driver);
+}
+
+ares_channel* grpc_ares_ev_driver_get_channel_locked(
+    grpc_ares_ev_driver* ev_driver) {
+  return &ev_driver->channel;
+}
+
+// Get the file descriptors used by the ev_driver's ares channel, register
+// driver_closure with these filedescriptors.
+static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) {
+  fd_node* new_list = nullptr;
+  if (!ev_driver->shutting_down) {
+    ares_socket_t socks[ARES_GETSOCK_MAXNUM];
+    int socks_bitmask =
+        ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM);
+    for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) {
+      if (ARES_GETSOCK_READABLE(socks_bitmask, i) ||
+          ARES_GETSOCK_WRITABLE(socks_bitmask, i)) {
+        fd_node* fdn = pop_fd_node_locked(&ev_driver->fds, socks[i]);
+        // Create a new fd_node if sock[i] is not in the fd_node list.
+        if (fdn == nullptr) {
+          fdn = static_cast<fd_node*>(gpr_malloc(sizeof(fd_node)));
+          fdn->grpc_polled_fd = grpc_core::NewGrpcPolledFdLocked(
+              socks[i], ev_driver->pollset_set);
+          gpr_log(GPR_DEBUG, "new fd: %s", fdn->grpc_polled_fd->GetName());
+          fdn->ev_driver = ev_driver;
+          fdn->readable_registered = false;
+          fdn->writable_registered = false;
+          fdn->already_shutdown = false;
+          GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable_locked, fdn,
+                            grpc_combiner_scheduler(ev_driver->combiner));
+          GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable_locked, fdn,
+                            grpc_combiner_scheduler(ev_driver->combiner));
+        }
+        fdn->next = new_list;
+        new_list = fdn;
+        // Register read_closure if the socket is readable and read_closure has
+        // not been registered with this socket.
+        if (ARES_GETSOCK_READABLE(socks_bitmask, i) &&
+            !fdn->readable_registered) {
+          grpc_ares_ev_driver_ref(ev_driver);
+          gpr_log(GPR_DEBUG, "notify read on: %s",
+                  fdn->grpc_polled_fd->GetName());
+          fdn->grpc_polled_fd->RegisterForOnReadableLocked(&fdn->read_closure);
+          fdn->readable_registered = true;
+        }
+        // Register write_closure if the socket is writable and write_closure
+        // has not been registered with this socket.
+        if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) &&
+            !fdn->writable_registered) {
+          gpr_log(GPR_DEBUG, "notify write on: %s",
+                  fdn->grpc_polled_fd->GetName());
+          grpc_ares_ev_driver_ref(ev_driver);
+          fdn->grpc_polled_fd->RegisterForOnWriteableLocked(
+              &fdn->write_closure);
+          fdn->writable_registered = true;
+        }
+      }
+    }
+  }
+  // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and
+  // are therefore no longer in use, so they can be shut down and removed from
+  // the list.
+  while (ev_driver->fds != nullptr) {
+    fd_node* cur = ev_driver->fds;
+    ev_driver->fds = ev_driver->fds->next;
+    fd_node_shutdown_locked(cur, "c-ares fd shutdown");
+    if (!cur->readable_registered && !cur->writable_registered) {
+      fd_node_destroy_locked(cur);
+    } else {
+      cur->next = new_list;
+      new_list = cur;
+    }
+  }
+  ev_driver->fds = new_list;
+  // If the ev driver has no working fd, all the tasks are done.
+  if (new_list == nullptr) {
+    ev_driver->working = false;
+    gpr_log(GPR_DEBUG, "ev driver stop working");
+  }
+}
+
+void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) {
+  if (!ev_driver->working) {
+    ev_driver->working = true;
+    grpc_ares_notify_on_event_locked(ev_driver);
+  }
+}
+
+#endif /* GRPC_ARES == 1 && defined(GRPC_POSIX_SOCKET_ARES_EV_DRIVER) */