src/core/lib/iomgr/tcp_uv.c - platform/external/grpc-grpc - Gitiles

 /*
  *
  * 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 "src/core/lib/iomgr/port.h"

 #ifdef GRPC_UV

 #include <limits.h>
 #include <string.h>

 #include <grpc/slice_buffer.h>

 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>

 #include "src/core/lib/iomgr/error.h"
 #include "src/core/lib/iomgr/network_status_tracker.h"
 #include "src/core/lib/iomgr/resource_quota.h"
 #include "src/core/lib/iomgr/tcp_uv.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
 #include "src/core/lib/support/string.h"

 grpc_tracer_flag grpc_tcp_trace = GRPC_TRACER_INITIALIZER(false, "tcp");

 typedef struct {
   grpc_endpoint base;
   gpr_refcount refcount;

   uv_write_t write_req;
   uv_shutdown_t shutdown_req;

   uv_tcp_t *handle;

   grpc_closure *read_cb;
   grpc_closure *write_cb;

   grpc_slice read_slice;
   grpc_slice_buffer *read_slices;
   grpc_slice_buffer *write_slices;
   uv_buf_t *write_buffers;

   grpc_resource_user *resource_user;

   bool shutting_down;

   char *peer_string;
   grpc_pollset *pollset;
 } grpc_tcp;

 static void tcp_free(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
   grpc_slice_unref_internal(exec_ctx, tcp->read_slice);
   grpc_resource_user_unref(exec_ctx, tcp->resource_user);
   gpr_free(tcp->handle);
   gpr_free(tcp->peer_string);
   gpr_free(tcp);
 }

 #ifndef NDEBUG
 #define TCP_UNREF(exec_ctx, tcp, reason) \
   tcp_unref((exec_ctx), (tcp), (reason), __FILE__, __LINE__)
 #define TCP_REF(tcp, reason) tcp_ref((tcp), (reason), __FILE__, __LINE__)
 static void tcp_unref(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp,
                       const char *reason, const char *file, int line) {
   if (GRPC_TRACER_ON(grpc_tcp_trace)) {
     gpr_atm val = gpr_atm_no_barrier_load(&tcp->refcount.count);
     gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
             "TCP unref %p : %s %" PRIdPTR " -> %" PRIdPTR, tcp, reason, val,
             val - 1);
   }
   if (gpr_unref(&tcp->refcount)) {
     tcp_free(exec_ctx, tcp);
   }
 }

 static void tcp_ref(grpc_tcp *tcp, const char *reason, const char *file,
                     int line) {
   if (GRPC_TRACER_ON(grpc_tcp_trace)) {
     gpr_atm val = gpr_atm_no_barrier_load(&tcp->refcount.count);
     gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
             "TCP   ref %p : %s %" PRIdPTR " -> %" PRIdPTR, tcp, reason, val,
             val + 1);
   }
   gpr_ref(&tcp->refcount);
 }
 #else
 #define TCP_UNREF(exec_ctx, tcp, reason) tcp_unref((exec_ctx), (tcp))
 #define TCP_REF(tcp, reason) tcp_ref((tcp))
 static void tcp_unref(grpc_exec_ctx *exec_ctx, grpc_tcp *tcp) {
   if (gpr_unref(&tcp->refcount)) {
     tcp_free(exec_ctx, tcp);
   }
 }

 static void tcp_ref(grpc_tcp *tcp) { gpr_ref(&tcp->refcount); }
 #endif

 static void uv_close_callback(uv_handle_t *handle) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_tcp *tcp = handle->data;
   TCP_UNREF(&exec_ctx, tcp, "destroy");
   grpc_exec_ctx_finish(&exec_ctx);
 }

 static grpc_slice alloc_read_slice(grpc_exec_ctx *exec_ctx,
                                    grpc_resource_user *resource_user) {
   return grpc_resource_user_slice_malloc(exec_ctx, resource_user,
                                          GRPC_TCP_DEFAULT_READ_SLICE_SIZE);
 }

 static void alloc_uv_buf(uv_handle_t *handle, size_t suggested_size,
                          uv_buf_t *buf) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_tcp *tcp = handle->data;
   (void)suggested_size;
   buf->base = (char *)GRPC_SLICE_START_PTR(tcp->read_slice);
   buf->len = GRPC_SLICE_LENGTH(tcp->read_slice);
   grpc_exec_ctx_finish(&exec_ctx);
 }

 static void read_callback(uv_stream_t *stream, ssize_t nread,
                           const uv_buf_t *buf) {
   grpc_slice sub;
   grpc_error *error;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_tcp *tcp = stream->data;
   grpc_closure *cb = tcp->read_cb;
   if (nread == 0) {
     // Nothing happened. Wait for the next callback
     return;
   }
   TCP_UNREF(&exec_ctx, tcp, "read");
   tcp->read_cb = NULL;
   // TODO(murgatroid99): figure out what the return value here means
   uv_read_stop(stream);
   if (nread == UV_EOF) {
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("EOF");
   } else if (nread > 0) {
     // Successful read
     sub = grpc_slice_sub_no_ref(tcp->read_slice, 0, (size_t)nread);
     grpc_slice_buffer_add(tcp->read_slices, sub);
     tcp->read_slice = alloc_read_slice(&exec_ctx, tcp->resource_user);
     error = GRPC_ERROR_NONE;
     if (GRPC_TRACER_ON(grpc_tcp_trace)) {
       size_t i;
       const char *str = grpc_error_string(error);
       gpr_log(GPR_DEBUG, "read: error=%s", str);

       for (i = 0; i < tcp->read_slices->count; i++) {
         char *dump = grpc_dump_slice(tcp->read_slices->slices[i],
                                      GPR_DUMP_HEX | GPR_DUMP_ASCII);
         gpr_log(GPR_DEBUG, "READ %p (peer=%s): %s", tcp, tcp->peer_string,
                 dump);
         gpr_free(dump);
       }
     }
   } else {
     // nread < 0: Error
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("TCP Read failed");
   }
   GRPC_CLOSURE_SCHED(&exec_ctx, cb, error);
   grpc_exec_ctx_finish(&exec_ctx);
 }

 static void uv_endpoint_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                              grpc_slice_buffer *read_slices, grpc_closure *cb) {
   grpc_tcp *tcp = (grpc_tcp *)ep;
   int status;
   grpc_error *error = GRPC_ERROR_NONE;
   GPR_ASSERT(tcp->read_cb == NULL);
   tcp->read_cb = cb;
   tcp->read_slices = read_slices;
   grpc_slice_buffer_reset_and_unref_internal(exec_ctx, read_slices);
   TCP_REF(tcp, "read");
   // TODO(murgatroid99): figure out what the return value here means
   status =
       uv_read_start((uv_stream_t *)tcp->handle, alloc_uv_buf, read_callback);
   if (status != 0) {
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("TCP Read failed at start");
     error =
         grpc_error_set_str(error, GRPC_ERROR_STR_OS_ERROR,
                            grpc_slice_from_static_string(uv_strerror(status)));
     GRPC_CLOSURE_SCHED(exec_ctx, cb, error);
   }
   if (GRPC_TRACER_ON(grpc_tcp_trace)) {
     const char *str = grpc_error_string(error);
     gpr_log(GPR_DEBUG, "Initiating read on %p: error=%s", tcp, str);
   }
 }

 static void write_callback(uv_write_t *req, int status) {
   grpc_tcp *tcp = req->data;
   grpc_error *error;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_closure *cb = tcp->write_cb;
   tcp->write_cb = NULL;
   TCP_UNREF(&exec_ctx, tcp, "write");
   if (status == 0) {
     error = GRPC_ERROR_NONE;
   } else {
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("TCP Write failed");
   }
   if (GRPC_TRACER_ON(grpc_tcp_trace)) {
     const char *str = grpc_error_string(error);
     gpr_log(GPR_DEBUG, "write complete on %p: error=%s", tcp, str);
   }
   gpr_free(tcp->write_buffers);
   grpc_resource_user_free(&exec_ctx, tcp->resource_user,
                           sizeof(uv_buf_t) * tcp->write_slices->count);
   GRPC_CLOSURE_SCHED(&exec_ctx, cb, error);
   grpc_exec_ctx_finish(&exec_ctx);
 }

 static void uv_endpoint_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                               grpc_slice_buffer *write_slices,
                               grpc_closure *cb) {
   grpc_tcp *tcp = (grpc_tcp *)ep;
   uv_buf_t *buffers;
   unsigned int buffer_count;
   unsigned int i;
   grpc_slice *slice;
   uv_write_t *write_req;

   if (GRPC_TRACER_ON(grpc_tcp_trace)) {
     size_t j;

     for (j = 0; j < write_slices->count; j++) {
       char *data = grpc_dump_slice(write_slices->slices[j],
                                    GPR_DUMP_HEX | GPR_DUMP_ASCII);
       gpr_log(GPR_DEBUG, "WRITE %p (peer=%s): %s", tcp, tcp->peer_string, data);
       gpr_free(data);
     }
   }

   if (tcp->shutting_down) {
     GRPC_CLOSURE_SCHED(exec_ctx, cb, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
                                          "TCP socket is shutting down"));
     return;
   }

   GPR_ASSERT(tcp->write_cb == NULL);
   tcp->write_slices = write_slices;
   GPR_ASSERT(tcp->write_slices->count <= UINT_MAX);
   if (tcp->write_slices->count == 0) {
     // No slices means we don't have to do anything,
     // and libuv doesn't like empty writes
     GRPC_CLOSURE_SCHED(exec_ctx, cb, GRPC_ERROR_NONE);
     return;
   }

   tcp->write_cb = cb;
   buffer_count = (unsigned int)tcp->write_slices->count;
   buffers = gpr_malloc(sizeof(uv_buf_t) * buffer_count);
   grpc_resource_user_alloc(exec_ctx, tcp->resource_user,
                            sizeof(uv_buf_t) * buffer_count, NULL);
   for (i = 0; i < buffer_count; i++) {
     slice = &tcp->write_slices->slices[i];
     buffers[i].base = (char *)GRPC_SLICE_START_PTR(*slice);
     buffers[i].len = GRPC_SLICE_LENGTH(*slice);
   }
   tcp->write_buffers = buffers;
   write_req = &tcp->write_req;
   write_req->data = tcp;
   TCP_REF(tcp, "write");
   // TODO(murgatroid99): figure out what the return value here means
   uv_write(write_req, (uv_stream_t *)tcp->handle, buffers, buffer_count,
            write_callback);
 }

 static void uv_add_to_pollset(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                               grpc_pollset *pollset) {
   // No-op. We're ignoring pollsets currently
   (void)exec_ctx;
   (void)ep;
   (void)pollset;
   grpc_tcp *tcp = (grpc_tcp *)ep;
   tcp->pollset = pollset;
 }

 static void uv_add_to_pollset_set(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                                   grpc_pollset_set *pollset) {
   // No-op. We're ignoring pollsets currently
   (void)exec_ctx;
   (void)ep;
   (void)pollset;
 }

 static void shutdown_callback(uv_shutdown_t *req, int status) {}

 static void uv_endpoint_shutdown(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                                  grpc_error *why) {
   grpc_tcp *tcp = (grpc_tcp *)ep;
   if (!tcp->shutting_down) {
     tcp->shutting_down = true;
     uv_shutdown_t *req = &tcp->shutdown_req;
     uv_shutdown(req, (uv_stream_t *)tcp->handle, shutdown_callback);
     grpc_resource_user_shutdown(exec_ctx, tcp->resource_user);
   }
   GRPC_ERROR_UNREF(why);
 }

 static void uv_destroy(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
   grpc_network_status_unregister_endpoint(ep);
   grpc_tcp *tcp = (grpc_tcp *)ep;
   uv_close((uv_handle_t *)tcp->handle, uv_close_callback);
 }

 static char *uv_get_peer(grpc_endpoint *ep) {
   grpc_tcp *tcp = (grpc_tcp *)ep;
   return gpr_strdup(tcp->peer_string);
 }

 static grpc_resource_user *uv_get_resource_user(grpc_endpoint *ep) {
   grpc_tcp *tcp = (grpc_tcp *)ep;
   return tcp->resource_user;
 }

 static int uv_get_fd(grpc_endpoint *ep) { return -1; }

 static grpc_endpoint_vtable vtable = {
     uv_endpoint_read,      uv_endpoint_write,    uv_add_to_pollset,
     uv_add_to_pollset_set, uv_endpoint_shutdown, uv_destroy,
     uv_get_resource_user,  uv_get_peer,          uv_get_fd};

 grpc_endpoint *grpc_tcp_create(uv_tcp_t *handle,
                                grpc_resource_quota *resource_quota,
                                char *peer_string) {
   grpc_tcp *tcp = (grpc_tcp *)gpr_malloc(sizeof(grpc_tcp));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;

   if (GRPC_TRACER_ON(grpc_tcp_trace)) {
     gpr_log(GPR_DEBUG, "Creating TCP endpoint %p", tcp);
   }

   /* Disable Nagle's Algorithm */
   uv_tcp_nodelay(handle, 1);

   memset(tcp, 0, sizeof(grpc_tcp));
   tcp->base.vtable = &vtable;
   tcp->handle = handle;
   handle->data = tcp;
   gpr_ref_init(&tcp->refcount, 1);
   tcp->peer_string = gpr_strdup(peer_string);
   tcp->shutting_down = false;
   tcp->resource_user = grpc_resource_user_create(resource_quota, peer_string);
   tcp->read_slice = alloc_read_slice(&exec_ctx, tcp->resource_user);
   /* Tell network status tracking code about the new endpoint */
   grpc_network_status_register_endpoint(&tcp->base);

 #ifndef GRPC_UV_TCP_HOLD_LOOP
   uv_unref((uv_handle_t *)handle);
 #endif

   grpc_exec_ctx_finish(&exec_ctx);
   return &tcp->base;
 }

 #endif /* GRPC_UV */
	/*
	*
	* 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 "src/core/lib/iomgr/port.h"

	#ifdef GRPC_UV

	#include <limits.h>
	#include <string.h>

	#include <grpc/slice_buffer.h>

	#include <grpc/support/alloc.h>
	#include <grpc/support/log.h>
	#include <grpc/support/string_util.h>

	#include "src/core/lib/iomgr/error.h"
	#include "src/core/lib/iomgr/network_status_tracker.h"
	#include "src/core/lib/iomgr/resource_quota.h"
	#include "src/core/lib/iomgr/tcp_uv.h"
	#include "src/core/lib/slice/slice_internal.h"
	#include "src/core/lib/slice/slice_string_helpers.h"
	#include "src/core/lib/support/string.h"

	grpc_tracer_flag grpc_tcp_trace = GRPC_TRACER_INITIALIZER(false, "tcp");

	typedef struct {
	grpc_endpoint base;
	gpr_refcount refcount;

	uv_write_t write_req;
	uv_shutdown_t shutdown_req;

	uv_tcp_t *handle;

	grpc_closure *read_cb;
	grpc_closure *write_cb;

	grpc_slice read_slice;
	grpc_slice_buffer *read_slices;
	grpc_slice_buffer *write_slices;
	uv_buf_t *write_buffers;

	grpc_resource_user *resource_user;

	bool shutting_down;

	char *peer_string;
	grpc_pollset *pollset;
	} grpc_tcp;

	static void tcp_free(grpc_exec_ctx exec_ctx, grpc_tcp tcp) {
	grpc_slice_unref_internal(exec_ctx, tcp->read_slice);
	grpc_resource_user_unref(exec_ctx, tcp->resource_user);
	gpr_free(tcp->handle);
	gpr_free(tcp->peer_string);
	gpr_free(tcp);
	}

	#ifndef NDEBUG
	#define TCP_UNREF(exec_ctx, tcp, reason) \
	tcp_unref((exec_ctx), (tcp), (reason), __FILE__, __LINE__)
	#define TCP_REF(tcp, reason) tcp_ref((tcp), (reason), __FILE__, __LINE__)
	static void tcp_unref(grpc_exec_ctx exec_ctx, grpc_tcp tcp,
	const char reason, const char file, int line) {
	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	gpr_atm val = gpr_atm_no_barrier_load(&tcp->refcount.count);
	gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
	"TCP unref %p : %s %" PRIdPTR " -> %" PRIdPTR, tcp, reason, val,
	val - 1);
	}
	if (gpr_unref(&tcp->refcount)) {
	tcp_free(exec_ctx, tcp);
	}
	}

	static void tcp_ref(grpc_tcp tcp, const char reason, const char *file,
	int line) {
	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	gpr_atm val = gpr_atm_no_barrier_load(&tcp->refcount.count);
	gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
	"TCP ref %p : %s %" PRIdPTR " -> %" PRIdPTR, tcp, reason, val,
	val + 1);
	}
	gpr_ref(&tcp->refcount);
	}
	#else
	#define TCP_UNREF(exec_ctx, tcp, reason) tcp_unref((exec_ctx), (tcp))
	#define TCP_REF(tcp, reason) tcp_ref((tcp))
	static void tcp_unref(grpc_exec_ctx exec_ctx, grpc_tcp tcp) {
	if (gpr_unref(&tcp->refcount)) {
	tcp_free(exec_ctx, tcp);
	}
	}

	static void tcp_ref(grpc_tcp *tcp) { gpr_ref(&tcp->refcount); }
	#endif

	static void uv_close_callback(uv_handle_t *handle) {
	grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
	grpc_tcp *tcp = handle->data;
	TCP_UNREF(&exec_ctx, tcp, "destroy");
	grpc_exec_ctx_finish(&exec_ctx);
	}

	static grpc_slice alloc_read_slice(grpc_exec_ctx *exec_ctx,
	grpc_resource_user *resource_user) {
	return grpc_resource_user_slice_malloc(exec_ctx, resource_user,
	GRPC_TCP_DEFAULT_READ_SLICE_SIZE);
	}

	static void alloc_uv_buf(uv_handle_t *handle, size_t suggested_size,
	uv_buf_t *buf) {
	grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
	grpc_tcp *tcp = handle->data;
	(void)suggested_size;
	buf->base = (char *)GRPC_SLICE_START_PTR(tcp->read_slice);
	buf->len = GRPC_SLICE_LENGTH(tcp->read_slice);
	grpc_exec_ctx_finish(&exec_ctx);
	}

	static void read_callback(uv_stream_t *stream, ssize_t nread,
	const uv_buf_t *buf) {
	grpc_slice sub;
	grpc_error *error;
	grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
	grpc_tcp *tcp = stream->data;
	grpc_closure *cb = tcp->read_cb;
	if (nread == 0) {
	// Nothing happened. Wait for the next callback
	return;
	}
	TCP_UNREF(&exec_ctx, tcp, "read");
	tcp->read_cb = NULL;
	// TODO(murgatroid99): figure out what the return value here means
	uv_read_stop(stream);
	if (nread == UV_EOF) {
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("EOF");
	} else if (nread > 0) {
	// Successful read
	sub = grpc_slice_sub_no_ref(tcp->read_slice, 0, (size_t)nread);
	grpc_slice_buffer_add(tcp->read_slices, sub);
	tcp->read_slice = alloc_read_slice(&exec_ctx, tcp->resource_user);
	error = GRPC_ERROR_NONE;
	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	size_t i;
	const char *str = grpc_error_string(error);
	gpr_log(GPR_DEBUG, "read: error=%s", str);

	for (i = 0; i < tcp->read_slices->count; i++) {
	char *dump = grpc_dump_slice(tcp->read_slices->slices[i],
	GPR_DUMP_HEX \| GPR_DUMP_ASCII);
	gpr_log(GPR_DEBUG, "READ %p (peer=%s): %s", tcp, tcp->peer_string,
	dump);
	gpr_free(dump);
	}
	}
	} else {
	// nread < 0: Error
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("TCP Read failed");
	}
	GRPC_CLOSURE_SCHED(&exec_ctx, cb, error);
	grpc_exec_ctx_finish(&exec_ctx);
	}

	static void uv_endpoint_read(grpc_exec_ctx exec_ctx, grpc_endpoint ep,
	grpc_slice_buffer read_slices, grpc_closure cb) {
	grpc_tcp tcp = (grpc_tcp )ep;
	int status;
	grpc_error *error = GRPC_ERROR_NONE;
	GPR_ASSERT(tcp->read_cb == NULL);
	tcp->read_cb = cb;
	tcp->read_slices = read_slices;
	grpc_slice_buffer_reset_and_unref_internal(exec_ctx, read_slices);
	TCP_REF(tcp, "read");
	// TODO(murgatroid99): figure out what the return value here means
	status =
	uv_read_start((uv_stream_t *)tcp->handle, alloc_uv_buf, read_callback);
	if (status != 0) {
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("TCP Read failed at start");
	error =
	grpc_error_set_str(error, GRPC_ERROR_STR_OS_ERROR,
	grpc_slice_from_static_string(uv_strerror(status)));
	GRPC_CLOSURE_SCHED(exec_ctx, cb, error);
	}
	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	const char *str = grpc_error_string(error);
	gpr_log(GPR_DEBUG, "Initiating read on %p: error=%s", tcp, str);
	}
	}

	static void write_callback(uv_write_t *req, int status) {
	grpc_tcp *tcp = req->data;
	grpc_error *error;
	grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
	grpc_closure *cb = tcp->write_cb;
	tcp->write_cb = NULL;
	TCP_UNREF(&exec_ctx, tcp, "write");
	if (status == 0) {
	error = GRPC_ERROR_NONE;
	} else {
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("TCP Write failed");
	}
	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	const char *str = grpc_error_string(error);
	gpr_log(GPR_DEBUG, "write complete on %p: error=%s", tcp, str);
	}
	gpr_free(tcp->write_buffers);
	grpc_resource_user_free(&exec_ctx, tcp->resource_user,
	sizeof(uv_buf_t) * tcp->write_slices->count);
	GRPC_CLOSURE_SCHED(&exec_ctx, cb, error);
	grpc_exec_ctx_finish(&exec_ctx);
	}

	static void uv_endpoint_write(grpc_exec_ctx exec_ctx, grpc_endpoint ep,
	grpc_slice_buffer *write_slices,
	grpc_closure *cb) {
	grpc_tcp tcp = (grpc_tcp )ep;
	uv_buf_t *buffers;
	unsigned int buffer_count;
	unsigned int i;
	grpc_slice *slice;
	uv_write_t *write_req;

	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	size_t j;

	for (j = 0; j < write_slices->count; j++) {
	char *data = grpc_dump_slice(write_slices->slices[j],
	GPR_DUMP_HEX \| GPR_DUMP_ASCII);
	gpr_log(GPR_DEBUG, "WRITE %p (peer=%s): %s", tcp, tcp->peer_string, data);
	gpr_free(data);
	}
	}

	if (tcp->shutting_down) {
	GRPC_CLOSURE_SCHED(exec_ctx, cb, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
	"TCP socket is shutting down"));
	return;
	}

	GPR_ASSERT(tcp->write_cb == NULL);
	tcp->write_slices = write_slices;
	GPR_ASSERT(tcp->write_slices->count <= UINT_MAX);
	if (tcp->write_slices->count == 0) {
	// No slices means we don't have to do anything,
	// and libuv doesn't like empty writes
	GRPC_CLOSURE_SCHED(exec_ctx, cb, GRPC_ERROR_NONE);
	return;
	}

	tcp->write_cb = cb;
	buffer_count = (unsigned int)tcp->write_slices->count;
	buffers = gpr_malloc(sizeof(uv_buf_t) * buffer_count);
	grpc_resource_user_alloc(exec_ctx, tcp->resource_user,
	sizeof(uv_buf_t) * buffer_count, NULL);
	for (i = 0; i < buffer_count; i++) {
	slice = &tcp->write_slices->slices[i];
	buffers[i].base = (char )GRPC_SLICE_START_PTR(slice);
	buffers[i].len = GRPC_SLICE_LENGTH(*slice);
	}
	tcp->write_buffers = buffers;
	write_req = &tcp->write_req;
	write_req->data = tcp;
	TCP_REF(tcp, "write");
	// TODO(murgatroid99): figure out what the return value here means
	uv_write(write_req, (uv_stream_t *)tcp->handle, buffers, buffer_count,
	write_callback);
	}

	static void uv_add_to_pollset(grpc_exec_ctx exec_ctx, grpc_endpoint ep,
	grpc_pollset *pollset) {
	// No-op. We're ignoring pollsets currently
	(void)exec_ctx;
	(void)ep;
	(void)pollset;
	grpc_tcp tcp = (grpc_tcp )ep;
	tcp->pollset = pollset;
	}

	static void uv_add_to_pollset_set(grpc_exec_ctx exec_ctx, grpc_endpoint ep,
	grpc_pollset_set *pollset) {
	// No-op. We're ignoring pollsets currently
	(void)exec_ctx;
	(void)ep;
	(void)pollset;
	}

	static void shutdown_callback(uv_shutdown_t *req, int status) {}

	static void uv_endpoint_shutdown(grpc_exec_ctx exec_ctx, grpc_endpoint ep,
	grpc_error *why) {
	grpc_tcp tcp = (grpc_tcp )ep;
	if (!tcp->shutting_down) {
	tcp->shutting_down = true;
	uv_shutdown_t *req = &tcp->shutdown_req;
	uv_shutdown(req, (uv_stream_t *)tcp->handle, shutdown_callback);
	grpc_resource_user_shutdown(exec_ctx, tcp->resource_user);
	}
	GRPC_ERROR_UNREF(why);
	}

	static void uv_destroy(grpc_exec_ctx exec_ctx, grpc_endpoint ep) {
	grpc_network_status_unregister_endpoint(ep);
	grpc_tcp tcp = (grpc_tcp )ep;
	uv_close((uv_handle_t *)tcp->handle, uv_close_callback);
	}

	static char uv_get_peer(grpc_endpoint ep) {
	grpc_tcp tcp = (grpc_tcp )ep;
	return gpr_strdup(tcp->peer_string);
	}

	static grpc_resource_user uv_get_resource_user(grpc_endpoint ep) {
	grpc_tcp tcp = (grpc_tcp )ep;
	return tcp->resource_user;
	}

	static int uv_get_fd(grpc_endpoint *ep) { return -1; }

	static grpc_endpoint_vtable vtable = {
	uv_endpoint_read, uv_endpoint_write, uv_add_to_pollset,
	uv_add_to_pollset_set, uv_endpoint_shutdown, uv_destroy,
	uv_get_resource_user, uv_get_peer, uv_get_fd};

	grpc_endpoint grpc_tcp_create(uv_tcp_t handle,
	grpc_resource_quota *resource_quota,
	char *peer_string) {
	grpc_tcp tcp = (grpc_tcp )gpr_malloc(sizeof(grpc_tcp));
	grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;

	if (GRPC_TRACER_ON(grpc_tcp_trace)) {
	gpr_log(GPR_DEBUG, "Creating TCP endpoint %p", tcp);
	}

	/* Disable Nagle's Algorithm */
	uv_tcp_nodelay(handle, 1);

	memset(tcp, 0, sizeof(grpc_tcp));
	tcp->base.vtable = &vtable;
	tcp->handle = handle;
	handle->data = tcp;
	gpr_ref_init(&tcp->refcount, 1);
	tcp->peer_string = gpr_strdup(peer_string);
	tcp->shutting_down = false;
	tcp->resource_user = grpc_resource_user_create(resource_quota, peer_string);
	tcp->read_slice = alloc_read_slice(&exec_ctx, tcp->resource_user);
	/* Tell network status tracking code about the new endpoint */
	grpc_network_status_register_endpoint(&tcp->base);

	#ifndef GRPC_UV_TCP_HOLD_LOOP
	uv_unref((uv_handle_t *)handle);
	#endif

	grpc_exec_ctx_finish(&exec_ctx);
	return &tcp->base;
	}

	#endif /* GRPC_UV */