pax_global_header00006660000000000000000000000064121222150540014504gustar00rootroot0000000000000052 comment=5847a0ba479caf01fe5435e948d6f05b2fb60676 schlock-0.2.1/000077500000000000000000000000001212221505400131325ustar00rootroot00000000000000schlock-0.2.1/.gitignore000066400000000000000000000001521212221505400151200ustar00rootroot00000000000000*~ #*# lib-cov *.seed *.log *.csv *.dat *.out *.pid *.gz pids logs results node_modules npm-debug.log schlock-0.2.1/.travis.yml000066400000000000000000000000551212221505400152430ustar00rootroot00000000000000language: node_js node_js: - 0.8 - 0.10 schlock-0.2.1/LICENSE000066400000000000000000000261361212221505400141470ustar00rootroot00000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. 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We also recommend that a file or class name and description of purpose be included on the same "printed page" as the copyright notice for easier identification within third-party archives. Copyright [yyyy] [name of copyright owner] 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. schlock-0.2.1/README.md000066400000000000000000000102371212221505400144140ustar00rootroot00000000000000Schlock ------- This is a poorly-crafted read-write lock system. It only works in-process, and doesn't lock things between processes. See also: > http://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock License ======= Copyright 2012, E14N Inc. 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. Overview ======== The module exports a single constructor that I call `Schlock` but you might want to call something smarter. var Schlock = require("schlock"); You need to create an instance to use it. I guess you could do this if you had multiple sets of resources (files and cache elements, say) that might share the same name. var fileSchlock = new Schlock(); var cacheSchlock = new Schlock(); // These won't block each other fileSchlock.writeLock("foo", ...); cacheSchlock.writeLock("foo", ...); Once you have a schlock, you use the `readLock`, `writeLock`, `readUnlock`, `writeUnlock` methods to manage resources. Read-only access to resources is pretty straightforward. var fname = "/tmp/myfile.txt"; fileSchlock.readLock(fname, function(err) { fs.readFile(fname, function(err, data) { fileSchlock.readUnlock(fname, function(err) { // do something with the data }); }); }); Read-write access is about the same: var fname = "/tmp/myfile.txt"; fileSchlock.writeLock(fname, function(err) { fs.readFile(fname, function(err, data) { var newData = modify(data); fs.writeFile(fname, newData, function(err) { fileSchlock.writeUnlock(fname, function(err) { // do something with the data }); }); }); }); I use [step](https://npmjs.org/package/step) to organize async stuff so it'd look more like this for me: var fname = "/tmp/myfile.txt"; Step( function() { fileSchlock.writeLock(fname, this); }, function(err) { if (err) throw err; fs.readFile(fname, this); }, function(err, data) { if (err) throw err; var newData = modify(data); fs.writeFile(fname, newData, this); }, function(err) { if (err) throw err; fileSchlock.writeUnlock(fname, this); }, function(err) { next(err); } ); ...which is a little less crazy. Multiple reads on the same resource can happen at the same time. Only one write on the same resource can happen at one time, and no reads can happen while the write is happening. Writes get precedence to prevent starvation. Filesystem ========== I made this so I could do atomic-ish changes to files, but note that it doesn't do `flock()` or any other operating-system-level locking automatically. You still have to do that yourself. API === * `new Schlock()` Creates a new `Schlock`. Doesn't pay attention to any parameters. * `readLock(name, callback)` Lock the resource `name` for reading and call `callback`. The callback takes a single parameter, an error. If the resource is currently write-locked, the callback will be queued to run once the write lock is unlocked. * `readUnlock(name, callback)` Unlock the resource `name` for reading and call `callback`. The callback takes a single parameter, an error. * `writeLock(name, callback)` Lock the resource `name` for reading and call `callback`. The callback takes a single parameter, an error. If the resource is currently write-locked or read-locked, the callback will be queued to run once the write lock is unlocked. * `writeUnlock(name, callback)` Unlock the resource `name` for writing and call `callback`. The callback takes a single parameter, an error. schlock-0.2.1/lib/000077500000000000000000000000001212221505400137005ustar00rootroot00000000000000schlock-0.2.1/lib/schlock.js000066400000000000000000000107321212221505400156670ustar00rootroot00000000000000// schlock.js // // Cheaply-made in-process lock broker // // Copyright 2012, StatusNet Inc. // // 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. var SchlockDoc = function(name, log) { var readers = 0, writers = 0, readQueue = [], writeQueue = []; var runLater = function(runme) { process.nextTick(function() { runme(null); }); }; var runNext = function() { var writer, reader; // XXX: assert(writers === 0); if (writeQueue.length > 0) { if (readers === 0) { if (log) log.info("Running queued writer for " + name); writer = writeQueue.shift(); writers++; runLater(writer); } } else if (readQueue.length > 0) { if (log) log.info("Running " + readQueue.length + " queued reader(s) for " + name); while (readQueue.length > 0) { reader = readQueue.shift(); readers++; runLater(reader); } } }; this.idle = function() { return (readers === 0 && writers === 0 && readQueue.length === 0 && writeQueue.length === 0); }; this.readLock = function(callback) { if (log) log.info("Read lock request for " + name); if (writers > 0 || writeQueue.length > 0) { if (log) log.info("Queueing reader for " + name); readQueue.push(callback); } else { if (log) log.info("Running reader immediately for " + name); readers++; runLater(callback); } }; this.writeLock = function(callback) { if (log) log.info("Write lock request for " + name); if (writers > 0 || readers > 0 || writeQueue.length > 0) { if (log) log.info("Queueing writer for " + name); writeQueue.push(callback); } else { if (log) log.info("Running writer immediately for " + name); writers++; runLater(callback); } }; this.readUnlock = function(callback) { if (log) log.info("Read unlock request for " + name); if (readers > 0) { if (log) log.info("Decrementing readers for " + name); readers--; } runLater(callback); runNext(); }; this.writeUnlock = function(callback) { if (log) log.info("Write unlock request for " + name); if (writers > 0) { if (log) log.info("Decrementing writers for " + name); writers--; } runLater(callback); runNext(); }; }; var Schlock = function(logParent) { var that = this, docs = {}, log = (logParent) ? logParent.child({component: "schlock"}) : null; var getDoc = function(name) { if (log) log.info("Getting lock record for " + name); if (!docs.hasOwnProperty(name)) { if (log) log.info("New lock record for " + name); docs[name] = new SchlockDoc(name, log); } return docs[name]; }; var rmDoc = function(name) { if (log) log.info("Removing lock record for " + name); delete docs[name]; }; this.readLock = function(name, callback) { var sd = getDoc(name); sd.readLock(callback); }; this.writeLock = function(name, callback) { var sd = getDoc(name); sd.writeLock(callback); }; this.readUnlock = function(name, callback) { var sd = getDoc(name); sd.readUnlock(callback); if (sd.idle()) { if (log) log.info("Lock record idle for " + name); rmDoc(name); } }; this.writeUnlock = function(name, callback) { var sd = getDoc(name); sd.writeUnlock(callback); if (sd.idle()) { if (log) log.info("Lock record idle for " + name); rmDoc(name); } }; }; module.exports = Schlock; schlock-0.2.1/package.json000066400000000000000000000021121212221505400154140ustar00rootroot00000000000000{ "name": "schlock", "description": "Poorly-crafted in-process lock broker", "homepage": "http://github.com/e14n/schlock", "version": "0.2.1", "keywords": ["schlock", "lock", "synchronization", "sync", "mutex", "readlock", "writelock", "read-write", "producer", "consumer"], "engines": { "node": ">= 0.8.0" }, "author": "Evan Prodromou ", "scripts": { "test": "vows -i test/*-test.js" }, "main": "./lib/schlock.js", "directories": { "lib": "./lib/" }, "devDependencies": { "vows": "0.7.x", "step": "0.0.x", "bunyan": "0.19.x" }, "dependencies": { }, "repository": { "type": "git", "url": "git://github.com/e14n/schlock.git" }, "licenses": [ { "type": "Apache 2.0", "url": "http://www.apache.org/licenses/LICENSE-2.0.html" } ] } schlock-0.2.1/test/000077500000000000000000000000001212221505400141115ustar00rootroot00000000000000schlock-0.2.1/test/logging-test.js000066400000000000000000000073741212221505400170650ustar00rootroot00000000000000// logging-test.js // // Test the logging // // Copyright 2012, E14N Inc. // // 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. var assert = require("assert"), vows = require("vows"), Step = require("step"), stream = require("stream"), util = require("util"), Logger = require("bunyan"); var suite = vows.describe("schlock logging interface"); var StreamMock = function() { this.writable = true; this.callback = null; this.output = null; }; util.inherits(StreamMock, stream.Stream); StreamMock.prototype.write = function(data) { var cb; this.output = data; if (this.callback) { cb = this.callback; process.nextTick(function() { cb(null, data); }); this.callback = null; } return true; }; StreamMock.prototype.end = function(data) { var cb; this.output = data; if (this.callback) { cb = this.callback; process.nextTick(function() { cb(null, data); }); this.callback = null; } }; StreamMock.prototype.setCallback = function(callback) { var mock = this; mock.callback = callback; }; suite.addBatch({ "When we require the module": { topic: function() { return require("../lib/schlock"); }, "it works": function(Schlock) { assert.ok(Schlock); }, "it returns the Schlock class": function(Schlock) { assert.isFunction(Schlock); }, "and we create a new Schlock": { topic: function(Schlock) { var str = new StreamMock(), callback = this.callback, log = new Logger({name: "schlock-test", stream: str}); callback(null, str, new Schlock(log)); }, "it works": function(err, str, schlock) { assert.ok(schlock); }, "and we do a read lock": { topic: function(str, schlock) { str.setCallback(this.callback); schlock.readLock("target1", function(err) {}); }, "it writes to the log": function(err, written) { assert.ifError(err); assert.ok(written); }, "and we do a read unlock": { topic: function(written, str, schlock) { str.setCallback(this.callback); schlock.readUnlock("target1", function(err) {}); }, "it writes to the log": function(err, written) { assert.ifError(err); assert.ok(written); } } }, "and we do a write lock": { topic: function(str, schlock) { str.setCallback(this.callback); schlock.writeLock("target2", function(err) {}); }, "it writes to the log": function(err, written) { assert.ifError(err); assert.ok(written); }, "and we do a write unlock": { topic: function(written, str, schlock) { str.setCallback(this.callback); schlock.writeUnlock("target2", function(err) {}); }, "it writes to the log": function(err, written) { assert.ifError(err); assert.ok(written); } } } } } }); suite["export"](module); schlock-0.2.1/test/schlock-test.js000066400000000000000000000324411212221505400170560ustar00rootroot00000000000000// schlock-test.js // // Test the schlock module // // Copyright 2012, StatusNet Inc. // // 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. var assert = require("assert"), vows = require("vows"), Step = require("step"); var suite = vows.describe("schlock module"); suite.addBatch({ "When we require the module": { topic: function() { return require("../lib/schlock"); }, "it works": function(Schlock) { assert.ok(Schlock); }, "it returns the Schlock class": function(Schlock) { assert.isFunction(Schlock); }, "and we create a new Schlock": { topic: function(Schlock) { return new Schlock(); }, "it has a readLock() method": function(schlock) { assert.isFunction(schlock.readLock); }, "it has a writeLock() method": function(schlock) { assert.isFunction(schlock.writeLock); }, "it has a readUnlock() method": function(schlock) { assert.isFunction(schlock.readUnlock); }, "it has a writeUnlock() method": function(schlock) { assert.isFunction(schlock.writeUnlock); }, "and we readLock a resource": { topic: function(schlock) { var resource1 = 42, value, callback = this.callback; Step( function() { schlock.readLock("resource1", this); }, function(err) { if (err) throw err; value = resource1; schlock.readUnlock("resource1", this); }, function(err) { if (err) { callback(err, null); } else { callback(null, value); } } ); }, "it works": function(err, value) { assert.ifError(err); assert.equal(value, 42); } }, "and we writeLock a resource": { topic: function(schlock) { var resource2 = 23, value, callback = this.callback; Step( function() { schlock.writeLock("resource2", this); }, function(err) { if (err) throw err; resource2 = 16; value = resource2; schlock.writeUnlock("resource2", this); }, function(err) { if (err) { callback(err, null); } else { callback(null, value); } } ); }, "it works": function(err, value) { assert.ifError(err); assert.equal(value, 16); } }, "and we readLock a resource multiple times": { topic: function(schlock) { var callback = this.callback, resource3 = 15; Step( function() { var i, group = this.group(), reader = function(cb) { return function(err) { var value; if (err) { cb(err, null); } else { value = resource3; schlock.readUnlock("resource3", function(err) { if (err) { cb(err, null); } else { cb(null, value); } }); } }; }; for (i = 0; i < 10; i++) { schlock.readLock("resource3", reader(group())); } }, function(err, results) { if (err) { callback(err, null); } else { callback(null, results); } } ); }, "it works": function(err, results) { var i; assert.ifError(err); assert.isArray(results); assert.lengthOf(results, 10); for (i = 0; i < 10; i++) { assert.equal(results[i], 15); } } }, "and we do a writer between readers": { topic: function(schlock) { var callback = this.callback, resource4 = 8; Step( function() { var i, group = this.group(), reader = function(cb) { var value; return function(err) { if (err) { cb(err, null); } else { value = resource4; schlock.readUnlock("resource4", function(err) { if (err) { cb(err, null); } else { cb(null, value); } }); } }; }, writer = function(cb) { var value; return function(err) { if (err) { cb(err, null); } else { resource4 = 4; value = resource4; schlock.writeUnlock("resource4", function(err) { if (err) { cb(err, null); } else { cb(null, value); } }); } }; }; for (i = 0; i < 10; i++) { schlock.readLock("resource4", reader(group())); } schlock.writeLock("resource4", writer(group())); for (i = 11; i < 21; i++) { schlock.readLock("resource4", reader(group())); } }, function(err, results) { if (err) { callback(err, null); } else { callback(null, results); } } ); }, "it works": function(err, results) { var i; assert.ifError(err); assert.isArray(results); assert.lengthOf(results, 21); for (i = 0; i < 10; i++) { assert.equal(results[i], 8); } assert.equal(results[10], 4); for (i = 11; i < 21; i++) { assert.equal(results[i], 4); } } }, "and we writeLock a resource multiple times": { topic: function(schlock) { var callback = this.callback, resource5 = 0; Step( function() { var i, group = this.group(), writer = function(cb) { return function(err) { var value; if (err) { cb(err, null); } else { resource5++; value = resource5; schlock.writeUnlock("resource5", function(err) { if (err) { cb(err, null); } else { cb(null, value); } }); } }; }; for (i = 0; i < 10; i++) { schlock.writeLock("resource5", writer(group())); } }, function(err, results) { if (err) { callback(err, null); } else { callback(null, results); } } ); }, "it works": function(err, results) { var i; assert.ifError(err); assert.isArray(results); assert.lengthOf(results, 10); for (i = 0; i < 10; i++) { assert.equal(results[i], i+1); } } }, "and we writeLock a resource twice in sequence": { topic: function(schlock) { var callback = this.callback, resource6 = 0; Step( function() { schlock.writeLock("resource6", this); }, function(err) { if (err) throw err; resource6++; schlock.writeUnlock("resource6", this); }, function(err) { if (err) throw err; schlock.writeLock("resource6", this); }, function(err) { if (err) throw err; resource6++; schlock.writeUnlock("resource6", this); }, function(err) { if (err) { callback(err, null); } else { callback(null, resource6); } } ); }, "it works": function(err, results) { assert.ifError(err); assert.isNumber(results); assert.equal(results, 2); } } } } }); suite["export"](module);