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node_modules/cls-bluebird/lib/shimCoroutine.js

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+'use strict';
+
+/*
+ * cls-bluebird
+ * Function to shim `Promise.coroutine`
+ *
+ * Works by binding the `.next()` and `.throw()` methods of generator to CLS context
+ * at time when coroutine is executed.
+ *
+ * In bluebird v3.x, running the coroutine internally calls `.lastly()` if cancellation is enabled.
+ * To prevent unnecessary binding of the `.lastly()` callback to CLS context, this patch
+ * temporarily disables the patch on `Promise.prototype.lastly`.
+ * NB This patch could break if bluebird internals change, but this is covered by the tests.
+ */
+
+// Modules
+var shimmer = require('shimmer');
+
+// Exports
+
+/**
+ * Patch `Promise.coroutine` or `Promise.spawn` to maintain current CLS context after all `yield` statements.
+ *
+ * @param {string} methodName - method name (either 'coroutine' or 'spawn')
+ * @param {Function} Promise - Bluebird Promise constructor to patch
+ * @param {Object} ns - CLS namespace to bind callbacks to
+ * @returns {undefined}
+ */
+module.exports = function(methodName, Promise, ns, v3) {
+	var lastlyPatched = Promise.prototype.lastly,
+		lastlyOriginal = Promise.prototype.lastly.__original;
+
+	// Patch method
+	shimmer.wrap(Promise, methodName, function(original) {
+		return function(generatorFunction, options) {
+			// NB If `generatorFunction` is not a function, do not alter it.
+			// Pass value directly to bluebird which will throw an error.
+			if (typeof generatorFunction === 'function') {
+				// Create proxy generator function
+				var generatorFunctionOriginal = generatorFunction;
+				generatorFunction = function() {
+					// Create generator from generator function
+					var generator = generatorFunctionOriginal.apply(this, arguments);
+
+					// Bind `.next()`, '.throw()' and `.return()` to current CLS context.
+					// NB CLS context is from when coroutine is called, not when created.
+					['next', 'throw', 'return'].forEach(function(name) {
+						if (typeof generator[name] === 'function') generator[name] = ns.bind(generator[name]);
+					});
+
+					return generator;
+				};
+			}
+
+			// Temporarily remove patch from `Promise.prototype.lastly` in bluebird v3
+			// to avoid unnecessary binding to CLS context.
+			var self = this;
+			if (methodName === 'spawn' && v3) {
+				return tempPatchLastly(function() {
+					return original.call(self, generatorFunction, options);
+				});
+			}
+
+			var fn = original.call(this, generatorFunction, options);
+
+			if (methodName === 'coroutine' && v3) {
+				return function() {
+					var self = this, args = arguments;
+					return tempPatchLastly(function() {
+						return fn.apply(self, args);
+					});
+				};
+			}
+
+			return fn;
+		};
+	});
+
+	function tempPatchLastly(fn) {
+		Promise.prototype.lastly = lastlyOriginal;
+		var res = fn();
+		Promise.prototype.lastly = lastlyPatched;
+		return res;
+	}
+};