buildTree/buildSFX/compileOutputs take optional compiler cache

lib/builder.js

@@ -214,7 +214,10 @@ Builder.prototype.config = function(config) {
   pluginLoader.config(cfg);
 };
 
-Builder.prototype.build = function(expression, outFile, opts) {
+/**
+ * @param {Object} [cache] - Optional cache for storing/reusing compiled modules from other calls to build/buildTree/buildSFX. The cache is populated with an entry for each `load` and is keyed on `load.name`.
+ */
+Builder.prototype.build = function(expression, outFile, opts, cache) {
   var self = this;
 
   // Allow passing opts as second argument.
@@ -230,7 +233,7 @@ Builder.prototype.build = function(expression, outFile, opts) {
 
   return this.trace(expression)
   .then(function(tree) {
-    return self.buildTree(tree, outFile, opts);
+    return self.buildTree(tree, outFile, opts, cache);
   });
 };
 
@@ -240,7 +243,10 @@ function addExtraOutputs(output, tree, opts) {
   });
 }
 
-Builder.prototype.buildTree = function(tree, outFile, opts) {
+/**
+ * @param {Object} [cache] - Optional cache for storing/reusing compiled modules, see also `build` method.
+ */
+Builder.prototype.buildTree = function(tree, outFile, opts, cache) {
   var loader = this.loader;
   var self = this;
 
@@ -252,7 +258,7 @@ Builder.prototype.buildTree = function(tree, outFile, opts) {
 
   opts = processOpts(opts, outFile);
 
-  return compileOutputs(loader, tree, opts, false)
+  return compileOutputs(loader, tree, opts, false, cache)
   .then(function(outputs) {
     return writeOutputs(opts, outputs, loader.baseURL);
   })
@@ -262,7 +268,10 @@ Builder.prototype.buildTree = function(tree, outFile, opts) {
   });
 };
 
-Builder.prototype.buildSFX = function(expression, outFile, opts) {
+/**
+ * @param {Object} [cache] - Optional cache for storing/reusing compiled modules, see also `build` method.
+ */
+Builder.prototype.buildSFX = function(expression, outFile, opts, cache) {
   var loader = this.loader;
   var self = this;
 
@@ -288,7 +297,7 @@ Builder.prototype.buildSFX = function(expression, outFile, opts) {
   return traceExpression(this, expression, true)
   .then(function(trace) {
     tree = trace.tree;
-    return compileOutputs(loader, tree, opts, trace.entryPoints);
+    return compileOutputs(loader, tree, opts, trace.entryPoints, cache);
   })
   .then(function(outputs) {
     return writeOutputs(opts, outputs, loader.baseURL);

lib/compile.js

@@ -3,6 +3,7 @@ var asp = require('rsvp').denodeify;
 var fs = require('fs');
 var path = require('path');
 var url = require('url');
+var createHash = require('crypto').createHash;
 
 var compilerMap = {
   'amd': '../compilers/amd',
@@ -12,6 +13,31 @@ var compilerMap = {
   'register': '../compilers/register'
 };
 
+function hashString(source) {
+  return createHash('md5').update(source).digest('hex');
+}
+
+function retrieveCachedOutput(cache, load) {
+  if (! cache)
+    return;
+
+  var entry = cache[load.name];
+  if (! entry)
+    return;
+
+  return hashString(load.source) === entry.sourceHash && entry.output;
+}
+
+function updateCacheEntry(cache, load, output) {
+  if (! cache)
+    return;
+
+  cache[load.name] = {
+    sourceHash: hashString(load.source),
+    output: output,
+  };
+}
+
 exports.compileLoad = compileLoad;
 function compileLoad(loader, load, opts) {
   if (load.metadata.build === false)
@@ -29,7 +55,7 @@ function compileLoad(loader, load, opts) {
 
 // compiledTree is load tree with "source" and "output" set
 exports.compileOutputs = compileOutputs;
-function compileOutputs(loader, tree, opts, sfxEntryPoints) {
+function compileOutputs(loader, tree, opts, sfxEntryPoints, cache) {
   var modules = Object.keys(tree);
 
   // store plugins with a bundle hook to allow post-processing
@@ -75,8 +101,15 @@ function compileOutputs(loader, tree, opts, sfxEntryPoints) {
       if (load.metadata.loaderModule && load.metadata.loaderModule.bundle)
         return;
 
+      var output = retrieveCachedOutput(cache, load);
+      if (output) {
+        outputs.push(output);
+        return;
+      }
+
       return Promise.resolve(compileLoad(loader, load, opts))
       .then(function(output) {
+        updateCacheEntry(cache, load, output);
         outputs.push(output);
       });
     }));

test/fixtures/test-cache-tree/simple.js

@@ -0,0 +1,3 @@
+define([], function(module) {
+  console.log('I hate caches');
+});

test/test-build-cache.js

@@ -0,0 +1,47 @@
+var Builder = require('../index');
+var expect = require('chai').expect;
+
+suite('Test compiler cache', function() {
+  var builder = new Builder('test/fixtures/test-cache-tree');
+  builder.config({ transpiler: 'babel' });
+
+  test('Use cache entry when available', function() {
+    var loadName = 'simple.js';
+    var outputPath = 'test/output/cached.js';
+    var cache = {};
+    var tree;
+
+    return builder.trace(loadName).then(function(_tree) {
+      tree = _tree;
+      return builder.buildTree(tree, null, {}, cache);
+    })
+    .then(function(output) {
+      var cacheEntry = cache[loadName];
+      expect(cacheEntry).to.be.an('object');
+      expect(cacheEntry.sourceHash).to.be.a('string');
+      var cacheOutput = cacheEntry.output;
+      expect(cacheOutput).to.be.an('object');
+
+      // poison cache
+      cacheOutput.source = cacheOutput.source.replace('hate', 'love');
+
+      return builder.buildTree(tree, null, {}, cache);
+    })
+    .then(function(output) {
+      // verify buildTree use poisoned cache rather than recompiling
+      var outputSource = output.source;
+      expect(outputSource).not.to.contain('hate caches');
+      expect(outputSource).to.contain('love caches');
+
+      // invalidate poisoned cache entry and rebuild
+      cache[loadName].sourceHash = 'out of date';
+      return builder.buildTree(tree, null, {}, cache);
+    })
+    .then(function(output) {
+      // verify original source is used once more
+      var outputSource = output.source;
+      expect(outputSource).to.contain('hate caches');
+      expect(outputSource).not.to.contain('love caches');
+    });
+  });
+});