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/*
*
* Copyright 2014, 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.
*
*/
var grpc = require('bindings')('grpc.node');
var common = require('./common');
var Duplex = require('stream').Duplex;
var util = require('util');
util.inherits(GrpcClientStream, Duplex);
/**
* Class for representing a gRPC client side stream as a Node stream. Extends
* from stream.Duplex.
* @constructor
* @param {grpc.Call} call Call object to proxy
* @param {function(*):Buffer=} serialize Serialization function for requests
* @param {function(Buffer):*=} deserialize Deserialization function for
* responses
*/
function GrpcClientStream(call, serialize, deserialize) {
Duplex.call(this, {objectMode: true});
if (!serialize) {
serialize = function(value) {
return value;
};
}
if (!deserialize) {
deserialize = function(value) {
return value;
};
}
var self = this;
var finished = false;
// Indicates that a read is currently pending
var reading = false;
// Indicates that a write is currently pending
var writing = false;
this._call = call;
/**
* Serialize a request value to a buffer. Always maps null to null. Otherwise
* uses the provided serialize function
* @param {*} value The value to serialize
* @return {Buffer} The serialized value
*/
this.serialize = function(value) {
if (value === null || value === undefined) {
return null;
}
return serialize(value);
};
/**
* Deserialize a response buffer to a value. Always maps null to null.
* Otherwise uses the provided deserialize function.
* @param {Buffer} buffer The buffer to deserialize
* @return {*} The deserialized value
*/
this.deserialize = function(buffer) {
if (buffer === null) {
return null;
}
return deserialize(buffer);
};
/**
* Callback to be called when a READ event is received. Pushes the data onto
* the read queue and starts reading again if applicable
* @param {grpc.Event} event READ event object
*/
function readCallback(event) {
if (finished) {
self.push(null);
return;
}
var data = event.data;
if (self.push(data) && data != null) {
self._call.startRead(readCallback);
} else {
reading = false;
}
}
call.invoke(function(event) {
self.emit('metadata', event.data);
}, function(event) {
finished = true;
self.emit('status', event.data);
}, 0);
this.on('finish', function() {
call.writesDone(function() {});
});
/**
* Start reading if there is not already a pending read. Reading will
* continue until self.push returns false (indicating reads should slow
* down) or the read data is null (indicating that there is no more data).
*/
this.startReading = function() {
if (finished) {
self.push(null);
} else {
if (!reading) {
reading = true;
self._call.startRead(readCallback);
}
}
};
}
/**
* Start reading. This is an implementation of a method needed for implementing
* stream.Readable.
* @param {number} size Ignored
*/
GrpcClientStream.prototype._read = function(size) {
this.startReading();
};
/**
* Attempt to write the given chunk. Calls the callback when done. This is an
* implementation of a method needed for implementing stream.Writable.
* @param {Buffer} chunk The chunk to write
* @param {string} encoding Ignored
* @param {function(Error=)} callback Ignored
*/
GrpcClientStream.prototype._write = function(chunk, encoding, callback) {
var self = this;
self._call.startWrite(chunk, function(event) {
callback();
}, 0);
};
/**
* Make a request on the channel to the given method with the given arguments
* @param {grpc.Channel} channel The channel on which to make the request
* @param {string} method The method to request
* @param {function(*):Buffer} serialize Serialization function for requests
* @param {function(Buffer):*} deserialize Deserialization function for
* responses
* @param {array=} metadata Array of metadata key/value pairs to add to the call
* @param {(number|Date)=} deadline The deadline for processing this request.
* Defaults to infinite future.
* @return {stream=} The stream of responses
*/
function makeRequest(channel,
method,
serialize,
deserialize,
metadata,
deadline) {
if (deadline === undefined) {
deadline = Infinity;
}
var call = new grpc.Call(channel, method, deadline);
if (metadata) {
call.addMetadata(metadata);
}
return new GrpcClientStream(call);
}
/**
* See documentation for makeRequest above
*/
exports.makeRequest = makeRequest;
/**
* Represents a client side gRPC channel associated with a single host.
*/
exports.Channel = grpc.Channel;
/**
* Status name to code number mapping
*/
exports.status = grpc.status;
/**
* Call error name to code number mapping
*/
exports.callError = grpc.callError;
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