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longrunning.js
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longrunning.js
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/*
* 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.
*/
var createBackoffSettings = require('./gax').createBackoffSettings;
var NormalApiCaller = require('./api_callable').NormalApiCaller;
var events = require('events');
var nextTick = require('process-nextick-args');
var util = require('util');
/**
* A callback to upack a google.protobuf.Any message.
* @callback anyDecoder
* @param {google.protobuf.Any} message - The message to unpacked.
* @return {Object} - The unpacked message.
*/
/**
* Describes the structure of a page-streaming call.
*
* @property {OperationsClient} operationsClient
* @property {anyDecoder} responseDecoder
* @property {anyDecoder} metadataDecoder
*
* @param {OperationsClient} operationsClient - The client used to poll or
* cancel an operation.
* @param {anyDecoder=} responseDecoder - The decoder to unpack
* the response message.
* @param {anyDecoder=} metadataDecoder - The decoder to unpack
* the metadata message.
*
* @constructor
*/
function LongrunningDescriptor(
operationsClient, responseDecoder, metadataDecoder) {
this.operationsClient = operationsClient;
this.responseDecoder = responseDecoder;
this.metadataDecoder = metadataDecoder;
}
LongrunningDescriptor.prototype.apiCaller = function() {
return new LongrunningApiCaller(this);
};
exports.LongrunningDescriptor = LongrunningDescriptor;
/**
* Creates an API caller that performs polling on a long running operation.
*
* @private
* @constructor
* @param {LongrunningDescriptor} longrunningDescriptor - Holds the
* decoders used for unpacking responses and the operationsClient
* used for polling the operation.
*/
function LongrunningApiCaller(longrunningDescriptor) {
NormalApiCaller.call(this);
this.longrunningDescriptor = longrunningDescriptor;
}
util.inherits(LongrunningApiCaller, NormalApiCaller);
LongrunningApiCaller.prototype.call = function(
apiCall, argument, settings, canceller) {
var self = this;
canceller.call(function(argument, callback) {
self._wrapOperation(apiCall, settings, argument, callback);
}, argument);
};
LongrunningApiCaller.prototype._wrapOperation = function(
apiCall, settings, argument, callback) {
var backoffSettings = settings.longrunning;
if (!backoffSettings) {
backoffSettings =
createBackoffSettings(100, 1.3, 60000, null, null, null, null);
}
var longrunningDescriptor = this.longrunningDescriptor;
return apiCall(argument, function(err, rawResponse) {
if (err) {
callback(err, null, rawResponse);
return;
}
var operation = new Operation(
rawResponse,
longrunningDescriptor,
backoffSettings,
settings
);
callback(null, operation, rawResponse);
});
};
/**
* Wrapper for a google.longrunnung.Operation.
*
* @constructor
*
* @param {google.longrunning.Operation} grpcOp - The operation to be wrapped.
* @param {LongrunningDescriptor} longrunningDescriptor - This defines the
* operations service client and unpacking mechanisms for the operation.
* @param {BackoffSettings} backoffSettings - The backoff settings used in
* in polling the operation.
* @param {CallOptions=} callOptions - CallOptions used in making get operation
* requests.
*/
function Operation(
grpcOp, longrunningDescriptor, backoffSettings, callOptions) {
events.EventEmitter.call(this);
this.completeListeners = 0;
this.hasActiveListeners = false;
this.latestResponse = grpcOp;
this.longrunningDescriptor = longrunningDescriptor;
this.result = null;
this.metadata = null;
this.backoffSettings = backoffSettings;
this._unpackResponse(grpcOp);
this._listenForEvents();
this._callOptions = callOptions;
}
util.inherits(Operation, events.EventEmitter);
/**
* Begin listening for events on the operation. This method keeps track of how
* many "complete" listeners are registered and removed, making sure polling is
* handled automatically.
*
* As long as there is one active "complete" listener, the connection is open.
* When there are no more listeners, the polling stops.
*
* @private
*/
Operation.prototype._listenForEvents = function() {
var self = this;
this.on('newListener', function(event) {
if (event === 'complete') {
self.completeListeners++;
if (!self.hasActiveListeners) {
self.hasActiveListeners = true;
self.startPolling_();
}
}
});
this.on('removeListener', function(event) {
if (event === 'complete' && --self.completeListeners === 0) {
self.hasActiveListeners = false;
}
});
};
/**
* Cancels current polling api call and cancels the operation.
*
* @return {Promise} the promise of the OperationsClient#cancelOperation api
* request.
*/
Operation.prototype.cancel = function() {
if (this.currentCallPromise_) {
this.currentCallPromise_.cancel();
}
var operationsClient = this.longrunningDescriptor.operationsClient;
return operationsClient.cancelOperation({name: this.latestResponse.name});
};
/**
* @callback GetOperationCallback
* @param {?Error} error
* @param {?Object} result
* @param {?Object} metadata
* @param {?google.longrunning.Operation} rawResponse
*/
/**
* Get the updated status of the operation. If the Operation has previously
* completed, this will use the status of the cached completed operation.
*
* - callback(err): Operation failed
* - callback(null, result, metadata, rawResponse): Operation complete
* - callback(null, null, metadata, rawResponse): Operation incomplete
*
* @param {getOperationCallback} callback - Callback to handle the polled
* operation result and metadata.
* @return {Promise|undefined} - This returns a promise if a callback is not specified.
* The promise resolves to an array where the first element is the unpacked
* result, the second element is the metadata, and the third element is the raw
* response of the api call. The promise rejects if the operation returns an
* error.
*/
Operation.prototype.getOperation = function(callback) {
var self = this;
var operationsClient = this.longrunningDescriptor.operationsClient;
function promisifyResponse() {
if (!callback) {
var PromiseCtor = self._callOptions.promise;
return new PromiseCtor(function(resolve, reject) {
if (self.latestResponse.error) {
var error = new Error(self.latestReponse.error.message);
error.code = self.latestReponse.error.code;
reject(error);
} else {
resolve([self.result, self.metadata, self.latestResponse]);
}
});
}
return;
}
if (this.latestResponse.done) {
this._unpackResponse(this.latestResponse, callback);
return promisifyResponse();
}
this.currentCallPromise_ =
operationsClient.getOperation(
{name: this.latestResponse.name}, this._callOptions);
var noCallbackPromise = this.currentCallPromise_
.then(function(responses) {
self.latestResponse = responses[0];
self._unpackResponse(responses[0], callback);
return promisifyResponse();
});
if (!callback) {
return noCallbackPromise;
}
};
Operation.prototype._unpackResponse = function(op, callback) {
var responseDecoder = this.longrunningDescriptor.responseDecoder;
var metadataDecoder = this.longrunningDescriptor.metadataDecoder;
var response;
var metadata;
if (op.done) {
if (op.result === 'error') {
var error = new Error(op.error.message);
error.code = op.error.code;
if (callback) {
callback(error);
}
return;
}
if (responseDecoder && op.response) {
response = responseDecoder(op.response.value);
this.result = response;
}
}
if (metadataDecoder && op.metadata) {
metadata = metadataDecoder(op.metadata.value);
this.metadata = metadata;
}
if (callback) {
callback(null, response, metadata, op);
}
};
/**
* Poll `getOperation` to check the operation's status. This runs a loop to ping
* using the backoff strategy specified at initialization.
*
* Note: This method is automatically called once a "complete" event handler is
* registered on the operation.
*
* @private
*/
Operation.prototype.startPolling_ = function() {
var self = this;
var now = new Date();
var delayMult = this.backoffSettings.retryDelayMultiplier;
var maxDelay = this.backoffSettings.maxRetryDelayMillis;
var delay = this.backoffSettings.initialRetryDelayMillis;
var deadline = Infinity;
if (this.backoffSettings.totalTimeoutMillis) {
deadline = now.getTime() + this.backoffSettings.totalTimeoutMillis;
}
var previousMetadataBytes;
if (this.latestResponse.metadata) {
previousMetadataBytes = this.latestResponse.metadata.value;
}
function emit() {
self.emit.apply(self, Array.prototype.slice.call(arguments, 0));
}
function retry() {
if (!self.hasActiveListeners) {
return;
}
if (now.getTime() >= deadline) {
nextTick(emit, 'error', new Error('Total timeout exceeded before ' +
'any response was received'));
return;
}
self.getOperation(function(err, result, metadata, rawResponse) {
if (err) {
nextTick(emit, 'error', err);
return;
}
if (!result) {
if (rawResponse.metadata && (!previousMetadataBytes ||
!rawResponse.metadata.value.equals(previousMetadataBytes))) {
nextTick(emit, 'progress', metadata, rawResponse);
previousMetadataBytes = rawResponse.metadata.value;
}
setTimeout(function() {
now = new Date();
delay = Math.min(delay * delayMult, maxDelay);
retry();
}, delay);
return;
}
nextTick(emit, 'complete', result, metadata, rawResponse);
});
}
retry();
};
/**
* Wraps the `complete` and `error` events in a Promise.
*
* @return {promise} - Promise that resolves on operation completion and rejects
* on operation error.
*/
Operation.prototype.promise = function() {
var self = this;
var PromiseCtor = this._callOptions.promise;
return new PromiseCtor(function(resolve, reject) {
self
.on('error', reject)
.on('complete', function(result, metadata, rawResponse) {
resolve([result, metadata, rawResponse]);
});
});
};
/**
* Method used to create Operation objects.
*
* @constructor
*
* @param {google.longrunning.Operation} op - The operation to be wrapped.
* @param {LongrunningDescriptor} longrunningDescriptor - This defines the
* operations service client and unpacking mechanisms for the operation.
* @param {BackoffSettings} backoffSettings - The backoff settings used in
* in polling the operation.
* @param {CallOptions=} callOptions - CallOptions used in making get operation
* requests.
*/
exports.operation =
function(op, longrunningDescriptor, backoffSettings, callOptions) {
return new Operation(
op, longrunningDescriptor, backoffSettings, callOptions);
};