webpack/lib/optimize/AggressiveSplittingPlugin.js

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
var path = require("path");

function AggressiveSplittingPlugin(options) {
	this.options = options || {};
	if(typeof this.options.minSize !== "number") this.options.minSize = 30 * 1024;
	if(typeof this.options.maxSize !== "number") this.options.maxSize = 50 * 1024;
	if(typeof this.options.chunkOverhead !== "number") this.options.chunkOverhead = 0;
	if(typeof this.options.entryChunkMultiplicator !== "number") this.options.entryChunkMultiplicator = 1;
}
module.exports = AggressiveSplittingPlugin;

function makeRelative(context) {
	return function(module) {
		var identifier = module.identifier();
		return identifier.split("|").map(function(str) {
			return str.split("!").map(function(str) {
				return path.relative(context, str);
			}).join("!");
		}).join("|");
	}
}

function toIndexOf(list) {
	return function(item) {
		return list.indexOf(item);
	}
}

function toChunkModuleIndices(modules) {
	return function(idx) {
		return modules[idx];
	}
}

function moveModuleBetween(oldChunk, newChunk) {
	return function(module) {
		oldChunk.moveModule(module, newChunk);
	}
}

function isNotAEntryModule(entryModule) {
	return function(module) {
		return entryModule !== module;
	}
}

function copyWithReason(obj) {
	var newObj = {};
	Object.keys(obj).forEach(function(key) {
		newObj[key] = obj[key];
	});
	if(!newObj.reasons || newObj.reasons.indexOf("aggressive-splitted") < 0)
		newObj.reasons = (newObj.reasons || []).concat("aggressive-splitted");
	return newObj;
}

AggressiveSplittingPlugin.prototype.apply = function(compiler) {
	var _this = this;
	compiler.plugin("compilation", function(compilation) {
		compilation.plugin("optimize-chunks-advanced", function(chunks) {
			var i, chunk, newChunk;
			var savedSplits = compilation.records && compilation.records.aggressiveSplits || [];
			var usedSplits = savedSplits;
			if(compilation._aggressiveSplittingSplits)
				usedSplits = usedSplits.concat(compilation._aggressiveSplittingSplits);
			var minSize = _this.options.minSize;
			var maxSize = _this.options.maxSize;
			// 1. try to restore to recorded splitting
			for(var j = 0; j < usedSplits.length; j++) {
				var splitData = usedSplits[j];
				for(i = 0; i < chunks.length; i++) {
					chunk = chunks[i];
					var chunkModuleNames = chunk.modules.map(makeRelative(compiler.context));

					if(chunkModuleNames.length < splitData.modules)
						continue;
					var moduleIndicies = splitData.modules.map(toIndexOf(chunkModuleNames));
					var hasAllModules = moduleIndicies.every(function(idx) {
						return idx >= 0;
					});
					if(hasAllModules) {
						if(chunkModuleNames.length > splitData.modules.length) {
							var selectedModules = moduleIndicies.map(toChunkModuleIndices(chunk.modules));
							newChunk = compilation.addChunk();
							selectedModules.forEach(moveModuleBetween(chunk, newChunk));
							chunk.split(newChunk);
							chunk.name = null;
							newChunk._fromAggressiveSplitting = true;
							if(j < savedSplits.length)
								newChunk._fromAggressiveSplittingIndex = j;
							if(typeof splitData.id === "number") newChunk.id = splitData.id;
							newChunk.origins = chunk.origins.map(copyWithReason);
							chunk.origins = chunk.origins.map(copyWithReason);
							return true;
						} else {
							if(j < savedSplits.length)
								chunk._fromAggressiveSplittingIndex = j;
							chunk.name = null;
							if(typeof splitData.id === "number") chunk.id = splitData.id;
						}
					}
				}
			}
			// 2. for any other chunk which isn't splitted yet, split it
			for(i = 0; i < chunks.length; i++) {
				chunk = chunks[i];
				var size = chunk.size(_this.options);
				if(size > maxSize && chunk.modules.length > 1) {
					newChunk = compilation.addChunk();
					var modules = chunk.modules
						.filter(isNotAEntryModule(chunk.entryModule))
						.sort(function(a, b) {
							a = a.identifier();
							b = b.identifier();
							if(a > b) return 1;
							if(a < b) return -1;
							return 0;
						});
					for(var k = 0; k < modules.length; k++) {
						chunk.moveModule(modules[k], newChunk);
						var newSize = newChunk.size(_this.options);
						var chunkSize = chunk.size(_this.options);
						// break early if it's fine
						if(chunkSize < maxSize && newSize < maxSize && newSize >= minSize && chunkSize >= minSize)
							break;
						if(newSize > maxSize && k === 0) {
							// break if there is a single module which is bigger than maxSize
							break;
						}
						if(newSize > maxSize || chunkSize < minSize) {
							// move it back
							newChunk.moveModule(modules[k], chunk);
							// check if it's fine now
							if(newSize < maxSize && newSize >= minSize && chunkSize >= minSize)
								break;
						}
					}
					if(newChunk.modules.length > 0) {
						chunk.split(newChunk);
						chunk.name = null;
						newChunk.origins = chunk.origins.map(copyWithReason);
						chunk.origins = chunk.origins.map(copyWithReason);
						compilation._aggressiveSplittingSplits = (compilation._aggressiveSplittingSplits || []).concat({
							modules: newChunk.modules.map(makeRelative(compiler.context))
						});
						return true;
					} else {
						chunks.splice(chunks.indexOf(newChunk), 1);
					}
				}
			}
		});
		compilation.plugin("record-hash", function(records) {
			// 3. save to made splittings to records
			var minSize = _this.options.minSize;
			var maxSize = _this.options.maxSize;
			if(!records.aggressiveSplits) records.aggressiveSplits = [];
			compilation.chunks.forEach(function(chunk) {
				if(chunk.hasEntryModule()) return;
				var size = chunk.size(_this.options);
				var incorrectSize = size < minSize;
				var modules = chunk.modules.map(makeRelative(compiler.context));
				if(typeof chunk._fromAggressiveSplittingIndex === "undefined") {
					if(incorrectSize) return;
					chunk.recorded = true;
					records.aggressiveSplits.push({
						modules: modules,
						hash: chunk.hash,
						id: chunk.id
					});
				} else {
					var splitData = records.aggressiveSplits[chunk._fromAggressiveSplittingIndex];
					if(splitData.hash !== chunk.hash || incorrectSize) {
						if(chunk._fromAggressiveSplitting) {
							chunk._aggressiveSplittingInvalid = true;
							splitData.invalid = true;
						} else {
							splitData.hash = chunk.hash;
						}
					}
				}
			});
			records.aggressiveSplits = records.aggressiveSplits.filter(function(splitData) {
				return !splitData.invalid;
			});
		});
		compilation.plugin("need-additional-seal", function(callback) {
			var invalid = this.chunks.some(function(chunk) {
				return chunk._aggressiveSplittingInvalid;
			});
			if(invalid)
				return true;
		});
	});
};