src/ruby/ext/grpc/rb_channel.c - platform/external/grpc-grpc - Gitiles

 /*
  *
  * Copyright 2015, 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 <ruby/ruby.h>

 #include "rb_grpc_imports.generated.h"
 #include "rb_channel.h"

 #include <grpc/grpc.h>
 #include <grpc/grpc_security.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/time.h>
 #include "rb_grpc.h"
 #include "rb_call.h"
 #include "rb_channel_args.h"
 #include "rb_channel_credentials.h"
 #include "rb_completion_queue.h"
 #include "rb_server.h"

 /* id_channel is the name of the hidden ivar that preserves a reference to the
  * channel on a call, so that calls are not GCed before their channel.  */
 static ID id_channel;

 /* id_target is the name of the hidden ivar that preserves a reference to the
  * target string used to create the call, preserved so that it does not get
  * GCed before the channel */
 static ID id_target;

 /* id_insecure_channel is used to indicate that a channel is insecure */
 static VALUE id_insecure_channel;

 /* grpc_rb_cChannel is the ruby class that proxies grpc_channel. */
 static VALUE grpc_rb_cChannel = Qnil;

 /* Used during the conversion of a hash to channel args during channel setup */
 static VALUE grpc_rb_cChannelArgs;

 /* grpc_rb_channel wraps a grpc_channel. */
 typedef struct grpc_rb_channel {
   VALUE credentials;

   /* The actual channel */
   grpc_channel *wrapped;
   grpc_completion_queue *queue;
 } grpc_rb_channel;

 /* Destroys Channel instances. */
 static void grpc_rb_channel_free(void *p) {
   grpc_rb_channel *ch = NULL;
   if (p == NULL) {
     return;
   };
   ch = (grpc_rb_channel *)p;

   if (ch->wrapped != NULL) {
     grpc_channel_destroy(ch->wrapped);
     grpc_rb_completion_queue_destroy(ch->queue);
   }

   xfree(p);
 }

 /* Protects the mark object from GC */
 static void grpc_rb_channel_mark(void *p) {
   grpc_rb_channel *channel = NULL;
   if (p == NULL) {
     return;
   }
   channel = (grpc_rb_channel *)p;
   if (channel->credentials != Qnil) {
     rb_gc_mark(channel->credentials);
   }
 }

 static rb_data_type_t grpc_channel_data_type = {
     "grpc_channel",
     {grpc_rb_channel_mark, grpc_rb_channel_free, GRPC_RB_MEMSIZE_UNAVAILABLE,
      {NULL, NULL}},
     NULL, NULL,
 #ifdef RUBY_TYPED_FREE_IMMEDIATELY
     RUBY_TYPED_FREE_IMMEDIATELY
 #endif
 };

 /* Allocates grpc_rb_channel instances. */
 static VALUE grpc_rb_channel_alloc(VALUE cls) {
   grpc_rb_channel *wrapper = ALLOC(grpc_rb_channel);
   wrapper->wrapped = NULL;
   wrapper->credentials = Qnil;
   return TypedData_Wrap_Struct(cls, &grpc_channel_data_type, wrapper);
 }

 /*
   call-seq:
     insecure_channel = Channel:new("myhost:8080", {'arg1': 'value1'},
                                    :this_channel_is_insecure)
     creds = ...
     secure_channel = Channel:new("myhost:443", {'arg1': 'value1'}, creds)

   Creates channel instances. */
 static VALUE grpc_rb_channel_init(int argc, VALUE *argv, VALUE self) {
   VALUE channel_args = Qnil;
   VALUE credentials = Qnil;
   VALUE target = Qnil;
   grpc_rb_channel *wrapper = NULL;
   grpc_channel *ch = NULL;
   grpc_channel_credentials *creds = NULL;
   char *target_chars = NULL;
   grpc_channel_args args;
   MEMZERO(&args, grpc_channel_args, 1);

   /* "3" == 3 mandatory args */
   rb_scan_args(argc, argv, "3", &target, &channel_args, &credentials);

   TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   target_chars = StringValueCStr(target);
   grpc_rb_hash_convert_to_channel_args(channel_args, &args);
   if (TYPE(credentials) == T_SYMBOL) {
     if (id_insecure_channel != SYM2ID(credentials)) {
       rb_raise(rb_eTypeError,
                "bad creds symbol, want :this_channel_is_insecure");
       return Qnil;
     }
     ch = grpc_insecure_channel_create(target_chars, &args, NULL);
   } else {
     wrapper->credentials = credentials;
     creds = grpc_rb_get_wrapped_channel_credentials(credentials);
     ch = grpc_secure_channel_create(creds, target_chars, &args, NULL);
   }
   if (args.args != NULL) {
     xfree(args.args); /* Allocated by grpc_rb_hash_convert_to_channel_args */
   }
   if (ch == NULL) {
     rb_raise(rb_eRuntimeError, "could not create an rpc channel to target:%s",
              target_chars);
     return Qnil;
   }
   rb_ivar_set(self, id_target, target);
   wrapper->wrapped = ch;
   wrapper->queue = grpc_completion_queue_create(NULL);
   return self;
 }

 /*
   call-seq:
     insecure_channel = Channel:new("myhost:8080", {'arg1': 'value1'})
     creds = ...
     secure_channel = Channel:new("myhost:443", {'arg1': 'value1'}, creds)

   Creates channel instances. */
 static VALUE grpc_rb_channel_get_connectivity_state(int argc, VALUE *argv,
                                                     VALUE self) {
   VALUE try_to_connect = Qfalse;
   grpc_rb_channel *wrapper = NULL;
   grpc_channel *ch = NULL;

   /* "01" == 0 mandatory args, 1 (try_to_connect) is optional */
   rb_scan_args(argc, argv, "01", try_to_connect);

   TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   ch = wrapper->wrapped;
   if (ch == NULL) {
     rb_raise(rb_eRuntimeError, "closed!");
     return Qnil;
   }
   return NUM2LONG(
       grpc_channel_check_connectivity_state(ch, (int)try_to_connect));
 }

 /* Watch for a change in connectivity state.

    Once the channel connectivity state is different from the last observed
    state, tag will be enqueued on cq with success=1

    If deadline expires BEFORE the state is changed, tag will be enqueued on
    the completion queue with success=0 */
 static VALUE grpc_rb_channel_watch_connectivity_state(VALUE self,
                                                       VALUE last_state,
                                                       VALUE deadline) {
   grpc_rb_channel *wrapper = NULL;
   grpc_channel *ch = NULL;
   grpc_completion_queue *cq = NULL;

   void *tag = wrapper;

   grpc_event event;

   TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   ch = wrapper->wrapped;
   cq = wrapper->queue;
   if (ch == NULL) {
     rb_raise(rb_eRuntimeError, "closed!");
     return Qnil;
   }
   grpc_channel_watch_connectivity_state(
       ch,
       (grpc_connectivity_state)NUM2LONG(last_state),
       grpc_rb_time_timeval(deadline, /* absolute time */ 0),
       cq,
       tag);

   event = rb_completion_queue_pluck(cq, tag,
                                     gpr_inf_future(GPR_CLOCK_REALTIME), NULL);

   if (event.success) {
     return Qtrue;
   } else {
     return Qfalse;
   }
 }

 /* Create a call given a grpc_channel, in order to call method. The request
    is not sent until grpc_call_invoke is called. */
 static VALUE grpc_rb_channel_create_call(VALUE self, VALUE parent,
                                          VALUE mask, VALUE method,
                                          VALUE host, VALUE deadline) {
   VALUE res = Qnil;
   grpc_rb_channel *wrapper = NULL;
   grpc_call *call = NULL;
   grpc_call *parent_call = NULL;
   grpc_channel *ch = NULL;
   grpc_completion_queue *cq = NULL;
   int flags = GRPC_PROPAGATE_DEFAULTS;
   char *method_chars = StringValueCStr(method);
   char *host_chars = NULL;
   if (host != Qnil) {
     host_chars = StringValueCStr(host);
   }
   if (mask != Qnil) {
     flags = NUM2UINT(mask);
   }
   if (parent != Qnil) {
     parent_call = grpc_rb_get_wrapped_call(parent);
   }

   cq = grpc_completion_queue_create(NULL);
   TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   ch = wrapper->wrapped;
   if (ch == NULL) {
     rb_raise(rb_eRuntimeError, "closed!");
     return Qnil;
   }

   call = grpc_channel_create_call(ch, parent_call, flags, cq, method_chars,
                                   host_chars, grpc_rb_time_timeval(
                                       deadline,
                                       /* absolute time */ 0), NULL);
   if (call == NULL) {
     rb_raise(rb_eRuntimeError, "cannot create call with method %s",
              method_chars);
     return Qnil;
   }
   res = grpc_rb_wrap_call(call, cq);

   /* Make this channel an instance attribute of the call so that it is not GCed
    * before the call. */
   rb_ivar_set(res, id_channel, self);
   return res;
 }


 /* Closes the channel, calling it's destroy method */
 static VALUE grpc_rb_channel_destroy(VALUE self) {
   grpc_rb_channel *wrapper = NULL;
   grpc_channel *ch = NULL;

   TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   ch = wrapper->wrapped;
   if (ch != NULL) {
     grpc_channel_destroy(ch);
     wrapper->wrapped = NULL;
   }

   return Qnil;
 }


 /* Called to obtain the target that this channel accesses. */
 static VALUE grpc_rb_channel_get_target(VALUE self) {
   grpc_rb_channel *wrapper = NULL;
   VALUE res = Qnil;
   char* target = NULL;

   TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   target = grpc_channel_get_target(wrapper->wrapped);
   res = rb_str_new2(target);
   gpr_free(target);

   return res;
 }

 static void Init_grpc_propagate_masks() {
   /* Constants representing call propagation masks in grpc.h */
   VALUE grpc_rb_mPropagateMasks = rb_define_module_under(
       grpc_rb_mGrpcCore, "PropagateMasks");
   rb_define_const(grpc_rb_mPropagateMasks, "DEADLINE",
                   UINT2NUM(GRPC_PROPAGATE_DEADLINE));
   rb_define_const(grpc_rb_mPropagateMasks, "CENSUS_STATS_CONTEXT",
                   UINT2NUM(GRPC_PROPAGATE_CENSUS_STATS_CONTEXT));
   rb_define_const(grpc_rb_mPropagateMasks, "CENSUS_TRACING_CONTEXT",
                   UINT2NUM(GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT));
   rb_define_const(grpc_rb_mPropagateMasks, "CANCELLATION",
                   UINT2NUM(GRPC_PROPAGATE_CANCELLATION));
   rb_define_const(grpc_rb_mPropagateMasks, "DEFAULTS",
                   UINT2NUM(GRPC_PROPAGATE_DEFAULTS));
 }

 static void Init_grpc_connectivity_states() {
   /* Constants representing call propagation masks in grpc.h */
   VALUE grpc_rb_mConnectivityStates = rb_define_module_under(
       grpc_rb_mGrpcCore, "ConnectivityStates");
   rb_define_const(grpc_rb_mConnectivityStates, "IDLE",
                   LONG2NUM(GRPC_CHANNEL_IDLE));
   rb_define_const(grpc_rb_mConnectivityStates, "CONNECTING",
                   LONG2NUM(GRPC_CHANNEL_CONNECTING));
   rb_define_const(grpc_rb_mConnectivityStates, "READY",
                   LONG2NUM(GRPC_CHANNEL_READY));
   rb_define_const(grpc_rb_mConnectivityStates, "TRANSIENT_FAILURE",
                   LONG2NUM(GRPC_CHANNEL_TRANSIENT_FAILURE));
   rb_define_const(grpc_rb_mConnectivityStates, "FATAL_FAILURE",
                   LONG2NUM(GRPC_CHANNEL_SHUTDOWN));
 }

 void Init_grpc_channel() {
   grpc_rb_cChannelArgs = rb_define_class("TmpChannelArgs", rb_cObject);
   grpc_rb_cChannel =
       rb_define_class_under(grpc_rb_mGrpcCore, "Channel", rb_cObject);

   /* Allocates an object managed by the ruby runtime */
   rb_define_alloc_func(grpc_rb_cChannel, grpc_rb_channel_alloc);

   /* Provides a ruby constructor and support for dup/clone. */
   rb_define_method(grpc_rb_cChannel, "initialize", grpc_rb_channel_init, -1);
   rb_define_method(grpc_rb_cChannel, "initialize_copy",
                    grpc_rb_cannot_init_copy, 1);

   /* Add ruby analogues of the Channel methods. */
   rb_define_method(grpc_rb_cChannel, "connectivity_state",
                    grpc_rb_channel_get_connectivity_state,
                    -1);
   rb_define_method(grpc_rb_cChannel, "watch_connectivity_state",
                    grpc_rb_channel_watch_connectivity_state, 4);
   rb_define_method(grpc_rb_cChannel, "create_call",
                    grpc_rb_channel_create_call, 5);
   rb_define_method(grpc_rb_cChannel, "target", grpc_rb_channel_get_target, 0);
   rb_define_method(grpc_rb_cChannel, "destroy", grpc_rb_channel_destroy, 0);
   rb_define_alias(grpc_rb_cChannel, "close", "destroy");

   id_channel = rb_intern("__channel");
   id_target = rb_intern("__target");
   rb_define_const(grpc_rb_cChannel, "SSL_TARGET",
                   ID2SYM(rb_intern(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)));
   rb_define_const(grpc_rb_cChannel, "ENABLE_CENSUS",
                   ID2SYM(rb_intern(GRPC_ARG_ENABLE_CENSUS)));
   rb_define_const(grpc_rb_cChannel, "MAX_CONCURRENT_STREAMS",
                   ID2SYM(rb_intern(GRPC_ARG_MAX_CONCURRENT_STREAMS)));
   rb_define_const(grpc_rb_cChannel, "MAX_MESSAGE_LENGTH",
                   ID2SYM(rb_intern(GRPC_ARG_MAX_MESSAGE_LENGTH)));
   id_insecure_channel = rb_intern("this_channel_is_insecure");
   Init_grpc_propagate_masks();
   Init_grpc_connectivity_states();
 }

 /* Gets the wrapped channel from the ruby wrapper */
 grpc_channel *grpc_rb_get_wrapped_channel(VALUE v) {
   grpc_rb_channel *wrapper = NULL;
   TypedData_Get_Struct(v, grpc_rb_channel, &grpc_channel_data_type, wrapper);
   return wrapper->wrapped;
 }
	/*
	*
	* Copyright 2015, 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 <ruby/ruby.h>

	#include "rb_grpc_imports.generated.h"
	#include "rb_channel.h"

	#include <grpc/grpc.h>
	#include <grpc/grpc_security.h>
	#include <grpc/support/alloc.h>
	#include <grpc/support/log.h>
	#include <grpc/support/time.h>
	#include "rb_grpc.h"
	#include "rb_call.h"
	#include "rb_channel_args.h"
	#include "rb_channel_credentials.h"
	#include "rb_completion_queue.h"
	#include "rb_server.h"

	/* id_channel is the name of the hidden ivar that preserves a reference to the
	* channel on a call, so that calls are not GCed before their channel. */
	static ID id_channel;

	/* id_target is the name of the hidden ivar that preserves a reference to the
	* target string used to create the call, preserved so that it does not get
	* GCed before the channel */
	static ID id_target;

	/* id_insecure_channel is used to indicate that a channel is insecure */
	static VALUE id_insecure_channel;

	/* grpc_rb_cChannel is the ruby class that proxies grpc_channel. */
	static VALUE grpc_rb_cChannel = Qnil;

	/* Used during the conversion of a hash to channel args during channel setup */
	static VALUE grpc_rb_cChannelArgs;

	/* grpc_rb_channel wraps a grpc_channel. */
	typedef struct grpc_rb_channel {
	VALUE credentials;

	/* The actual channel */
	grpc_channel *wrapped;
	grpc_completion_queue *queue;
	} grpc_rb_channel;

	/* Destroys Channel instances. */
	static void grpc_rb_channel_free(void *p) {
	grpc_rb_channel *ch = NULL;
	if (p == NULL) {
	return;
	};
	ch = (grpc_rb_channel *)p;

	if (ch->wrapped != NULL) {
	grpc_channel_destroy(ch->wrapped);
	grpc_rb_completion_queue_destroy(ch->queue);
	}

	xfree(p);
	}

	/* Protects the mark object from GC */
	static void grpc_rb_channel_mark(void *p) {
	grpc_rb_channel *channel = NULL;
	if (p == NULL) {
	return;
	}
	channel = (grpc_rb_channel *)p;
	if (channel->credentials != Qnil) {
	rb_gc_mark(channel->credentials);
	}
	}

	static rb_data_type_t grpc_channel_data_type = {
	"grpc_channel",
	{grpc_rb_channel_mark, grpc_rb_channel_free, GRPC_RB_MEMSIZE_UNAVAILABLE,
	{NULL, NULL}},
	NULL, NULL,
	#ifdef RUBY_TYPED_FREE_IMMEDIATELY
	RUBY_TYPED_FREE_IMMEDIATELY
	#endif
	};

	/* Allocates grpc_rb_channel instances. */
	static VALUE grpc_rb_channel_alloc(VALUE cls) {
	grpc_rb_channel *wrapper = ALLOC(grpc_rb_channel);
	wrapper->wrapped = NULL;
	wrapper->credentials = Qnil;
	return TypedData_Wrap_Struct(cls, &grpc_channel_data_type, wrapper);
	}

	/*
	call-seq:
	insecure_channel = Channel:new("myhost:8080", {'arg1': 'value1'},
	:this_channel_is_insecure)
	creds = ...
	secure_channel = Channel:new("myhost:443", {'arg1': 'value1'}, creds)

	Creates channel instances. */
	static VALUE grpc_rb_channel_init(int argc, VALUE *argv, VALUE self) {
	VALUE channel_args = Qnil;
	VALUE credentials = Qnil;
	VALUE target = Qnil;
	grpc_rb_channel *wrapper = NULL;
	grpc_channel *ch = NULL;
	grpc_channel_credentials *creds = NULL;
	char *target_chars = NULL;
	grpc_channel_args args;
	MEMZERO(&args, grpc_channel_args, 1);

	/* "3" == 3 mandatory args */
	rb_scan_args(argc, argv, "3", &target, &channel_args, &credentials);

	TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	target_chars = StringValueCStr(target);
	grpc_rb_hash_convert_to_channel_args(channel_args, &args);
	if (TYPE(credentials) == T_SYMBOL) {
	if (id_insecure_channel != SYM2ID(credentials)) {
	rb_raise(rb_eTypeError,
	"bad creds symbol, want :this_channel_is_insecure");
	return Qnil;
	}
	ch = grpc_insecure_channel_create(target_chars, &args, NULL);
	} else {
	wrapper->credentials = credentials;
	creds = grpc_rb_get_wrapped_channel_credentials(credentials);
	ch = grpc_secure_channel_create(creds, target_chars, &args, NULL);
	}
	if (args.args != NULL) {
	xfree(args.args); /* Allocated by grpc_rb_hash_convert_to_channel_args */
	}
	if (ch == NULL) {
	rb_raise(rb_eRuntimeError, "could not create an rpc channel to target:%s",
	target_chars);
	return Qnil;
	}
	rb_ivar_set(self, id_target, target);
	wrapper->wrapped = ch;
	wrapper->queue = grpc_completion_queue_create(NULL);
	return self;
	}

	/*
	call-seq:
	insecure_channel = Channel:new("myhost:8080", {'arg1': 'value1'})
	creds = ...
	secure_channel = Channel:new("myhost:443", {'arg1': 'value1'}, creds)

	Creates channel instances. */
	static VALUE grpc_rb_channel_get_connectivity_state(int argc, VALUE *argv,
	VALUE self) {
	VALUE try_to_connect = Qfalse;
	grpc_rb_channel *wrapper = NULL;
	grpc_channel *ch = NULL;

	/* "01" == 0 mandatory args, 1 (try_to_connect) is optional */
	rb_scan_args(argc, argv, "01", try_to_connect);

	TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	ch = wrapper->wrapped;
	if (ch == NULL) {
	rb_raise(rb_eRuntimeError, "closed!");
	return Qnil;
	}
	return NUM2LONG(
	grpc_channel_check_connectivity_state(ch, (int)try_to_connect));
	}

	/* Watch for a change in connectivity state.

	Once the channel connectivity state is different from the last observed
	state, tag will be enqueued on cq with success=1

	If deadline expires BEFORE the state is changed, tag will be enqueued on
	the completion queue with success=0 */
	static VALUE grpc_rb_channel_watch_connectivity_state(VALUE self,
	VALUE last_state,
	VALUE deadline) {
	grpc_rb_channel *wrapper = NULL;
	grpc_channel *ch = NULL;
	grpc_completion_queue *cq = NULL;

	void *tag = wrapper;

	grpc_event event;

	TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	ch = wrapper->wrapped;
	cq = wrapper->queue;
	if (ch == NULL) {
	rb_raise(rb_eRuntimeError, "closed!");
	return Qnil;
	}
	grpc_channel_watch_connectivity_state(
	ch,
	(grpc_connectivity_state)NUM2LONG(last_state),
	grpc_rb_time_timeval(deadline, /* absolute time */ 0),
	cq,
	tag);

	event = rb_completion_queue_pluck(cq, tag,
	gpr_inf_future(GPR_CLOCK_REALTIME), NULL);

	if (event.success) {
	return Qtrue;
	} else {
	return Qfalse;
	}
	}

	/* Create a call given a grpc_channel, in order to call method. The request
	is not sent until grpc_call_invoke is called. */
	static VALUE grpc_rb_channel_create_call(VALUE self, VALUE parent,
	VALUE mask, VALUE method,
	VALUE host, VALUE deadline) {
	VALUE res = Qnil;
	grpc_rb_channel *wrapper = NULL;
	grpc_call *call = NULL;
	grpc_call *parent_call = NULL;
	grpc_channel *ch = NULL;
	grpc_completion_queue *cq = NULL;
	int flags = GRPC_PROPAGATE_DEFAULTS;
	char *method_chars = StringValueCStr(method);
	char *host_chars = NULL;
	if (host != Qnil) {
	host_chars = StringValueCStr(host);
	}
	if (mask != Qnil) {
	flags = NUM2UINT(mask);
	}
	if (parent != Qnil) {
	parent_call = grpc_rb_get_wrapped_call(parent);
	}

	cq = grpc_completion_queue_create(NULL);
	TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	ch = wrapper->wrapped;
	if (ch == NULL) {
	rb_raise(rb_eRuntimeError, "closed!");
	return Qnil;
	}

	call = grpc_channel_create_call(ch, parent_call, flags, cq, method_chars,
	host_chars, grpc_rb_time_timeval(
	deadline,
	/* absolute time */ 0), NULL);
	if (call == NULL) {
	rb_raise(rb_eRuntimeError, "cannot create call with method %s",
	method_chars);
	return Qnil;
	}
	res = grpc_rb_wrap_call(call, cq);

	/* Make this channel an instance attribute of the call so that it is not GCed
	* before the call. */
	rb_ivar_set(res, id_channel, self);
	return res;
	}


	/* Closes the channel, calling it's destroy method */
	static VALUE grpc_rb_channel_destroy(VALUE self) {
	grpc_rb_channel *wrapper = NULL;
	grpc_channel *ch = NULL;

	TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	ch = wrapper->wrapped;
	if (ch != NULL) {
	grpc_channel_destroy(ch);
	wrapper->wrapped = NULL;
	}

	return Qnil;
	}


	/* Called to obtain the target that this channel accesses. */
	static VALUE grpc_rb_channel_get_target(VALUE self) {
	grpc_rb_channel *wrapper = NULL;
	VALUE res = Qnil;
	char* target = NULL;

	TypedData_Get_Struct(self, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	target = grpc_channel_get_target(wrapper->wrapped);
	res = rb_str_new2(target);
	gpr_free(target);

	return res;
	}

	static void Init_grpc_propagate_masks() {
	/* Constants representing call propagation masks in grpc.h */
	VALUE grpc_rb_mPropagateMasks = rb_define_module_under(
	grpc_rb_mGrpcCore, "PropagateMasks");
	rb_define_const(grpc_rb_mPropagateMasks, "DEADLINE",
	UINT2NUM(GRPC_PROPAGATE_DEADLINE));
	rb_define_const(grpc_rb_mPropagateMasks, "CENSUS_STATS_CONTEXT",
	UINT2NUM(GRPC_PROPAGATE_CENSUS_STATS_CONTEXT));
	rb_define_const(grpc_rb_mPropagateMasks, "CENSUS_TRACING_CONTEXT",
	UINT2NUM(GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT));
	rb_define_const(grpc_rb_mPropagateMasks, "CANCELLATION",
	UINT2NUM(GRPC_PROPAGATE_CANCELLATION));
	rb_define_const(grpc_rb_mPropagateMasks, "DEFAULTS",
	UINT2NUM(GRPC_PROPAGATE_DEFAULTS));
	}

	static void Init_grpc_connectivity_states() {
	/* Constants representing call propagation masks in grpc.h */
	VALUE grpc_rb_mConnectivityStates = rb_define_module_under(
	grpc_rb_mGrpcCore, "ConnectivityStates");
	rb_define_const(grpc_rb_mConnectivityStates, "IDLE",
	LONG2NUM(GRPC_CHANNEL_IDLE));
	rb_define_const(grpc_rb_mConnectivityStates, "CONNECTING",
	LONG2NUM(GRPC_CHANNEL_CONNECTING));
	rb_define_const(grpc_rb_mConnectivityStates, "READY",
	LONG2NUM(GRPC_CHANNEL_READY));
	rb_define_const(grpc_rb_mConnectivityStates, "TRANSIENT_FAILURE",
	LONG2NUM(GRPC_CHANNEL_TRANSIENT_FAILURE));
	rb_define_const(grpc_rb_mConnectivityStates, "FATAL_FAILURE",
	LONG2NUM(GRPC_CHANNEL_SHUTDOWN));
	}

	void Init_grpc_channel() {
	grpc_rb_cChannelArgs = rb_define_class("TmpChannelArgs", rb_cObject);
	grpc_rb_cChannel =
	rb_define_class_under(grpc_rb_mGrpcCore, "Channel", rb_cObject);

	/* Allocates an object managed by the ruby runtime */
	rb_define_alloc_func(grpc_rb_cChannel, grpc_rb_channel_alloc);

	/* Provides a ruby constructor and support for dup/clone. */
	rb_define_method(grpc_rb_cChannel, "initialize", grpc_rb_channel_init, -1);
	rb_define_method(grpc_rb_cChannel, "initialize_copy",
	grpc_rb_cannot_init_copy, 1);

	/* Add ruby analogues of the Channel methods. */
	rb_define_method(grpc_rb_cChannel, "connectivity_state",
	grpc_rb_channel_get_connectivity_state,
	-1);
	rb_define_method(grpc_rb_cChannel, "watch_connectivity_state",
	grpc_rb_channel_watch_connectivity_state, 4);
	rb_define_method(grpc_rb_cChannel, "create_call",
	grpc_rb_channel_create_call, 5);
	rb_define_method(grpc_rb_cChannel, "target", grpc_rb_channel_get_target, 0);
	rb_define_method(grpc_rb_cChannel, "destroy", grpc_rb_channel_destroy, 0);
	rb_define_alias(grpc_rb_cChannel, "close", "destroy");

	id_channel = rb_intern("__channel");
	id_target = rb_intern("__target");
	rb_define_const(grpc_rb_cChannel, "SSL_TARGET",
	ID2SYM(rb_intern(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)));
	rb_define_const(grpc_rb_cChannel, "ENABLE_CENSUS",
	ID2SYM(rb_intern(GRPC_ARG_ENABLE_CENSUS)));
	rb_define_const(grpc_rb_cChannel, "MAX_CONCURRENT_STREAMS",
	ID2SYM(rb_intern(GRPC_ARG_MAX_CONCURRENT_STREAMS)));
	rb_define_const(grpc_rb_cChannel, "MAX_MESSAGE_LENGTH",
	ID2SYM(rb_intern(GRPC_ARG_MAX_MESSAGE_LENGTH)));
	id_insecure_channel = rb_intern("this_channel_is_insecure");
	Init_grpc_propagate_masks();
	Init_grpc_connectivity_states();
	}

	/* Gets the wrapped channel from the ruby wrapper */
	grpc_channel *grpc_rb_get_wrapped_channel(VALUE v) {
	grpc_rb_channel *wrapper = NULL;
	TypedData_Get_Struct(v, grpc_rb_channel, &grpc_channel_data_type, wrapper);
	return wrapper->wrapped;
	}