1 /* 2 * Copyright (C) 2006 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.inject.internal; 18 19 import com.google.inject.internal.InjectorImpl.InjectorOptions; 20 import com.google.inject.spi.Dependency; 21 import java.util.IdentityHashMap; 22 import java.util.Map; 23 24 /** 25 * Internal context. Used to coordinate injections and support circular dependencies. 26 * 27 * @author crazybob@google.com (Bob Lee) 28 */ 29 final class InternalContext implements AutoCloseable { 30 31 private final InjectorOptions options; 32 33 private final Map<Object, ConstructionContext<?>> constructionContexts = 34 new IdentityHashMap<Object, ConstructionContext<?>>(); 35 36 /** Keeps track of the type that is currently being requested for injection. */ 37 private Dependency<?> dependency; 38 39 /** 40 * Keeps track of the hierarchy of types needed during injection. 41 * 42 * <p>This is a pairwise combination of dependencies and sources, with dependencies or keys on 43 * even indices, and sources on odd indices. This structure is to avoid the memory overhead of 44 * DependencyAndSource objects, which can add to several tens of megabytes in large applications. 45 */ 46 private Object[] dependencyStack = new Object[16]; 47 48 private int dependencyStackSize = 0; 49 50 51 /** 52 * The number of times {@link #enter()} has been called + 1 for initial construction. This value 53 * is decremented when {@link #exit()} is called. 54 */ 55 private int enterCount; 56 57 /** 58 * A single element array to clear when the {@link #enterCount} hits {@code 0}. 59 * 60 * <p>This is the value stored in the {@code InjectorImpl.localContext} thread local. 61 */ 62 private final Object[] toClear; 63 InternalContext(InjectorOptions options, Object[] toClear)64 InternalContext(InjectorOptions options, Object[] toClear) { 65 this.options = options; 66 this.toClear = toClear; 67 this.enterCount = 1; 68 } 69 70 /** Should only be called by InjectorImpl.enterContext(). */ enter()71 void enter() { 72 enterCount++; 73 } 74 75 /** Should be called any any method that received an instance via InjectorImpl.enterContext(). */ 76 @Override close()77 public void close() { 78 int newCount = --enterCount; 79 if (newCount < 0) { 80 throw new IllegalStateException("Called close() too many times"); 81 } 82 if (newCount == 0) { 83 toClear[0] = null; 84 } 85 } 86 getInjectorOptions()87 InjectorOptions getInjectorOptions() { 88 return options; 89 } 90 91 @SuppressWarnings("unchecked") getConstructionContext(Object key)92 <T> ConstructionContext<T> getConstructionContext(Object key) { 93 ConstructionContext<T> constructionContext = 94 (ConstructionContext<T>) constructionContexts.get(key); 95 if (constructionContext == null) { 96 constructionContext = new ConstructionContext<>(); 97 constructionContexts.put(key, constructionContext); 98 } 99 return constructionContext; 100 } 101 getDependency()102 Dependency<?> getDependency() { 103 return dependency; 104 } 105 106 /** Sets the new current dependency & adds it to the state. */ pushDependency(Dependency<?> dependency, Object source)107 Dependency<?> pushDependency(Dependency<?> dependency, Object source) { 108 Dependency<?> previous = this.dependency; 109 this.dependency = dependency; 110 doPushState(dependency, source); 111 return previous; 112 } 113 114 115 /** Pops the current state & sets the new dependency. */ popStateAndSetDependency(Dependency<?> newDependency)116 void popStateAndSetDependency(Dependency<?> newDependency) { 117 popState(); 118 this.dependency = newDependency; 119 } 120 121 122 /** Adds to the state without setting the dependency. */ pushState(com.google.inject.Key<?> key, Object source)123 void pushState(com.google.inject.Key<?> key, Object source) { 124 doPushState(key, source); 125 } 126 127 doPushState(Object dependencyOrKey, Object source)128 private void doPushState(Object dependencyOrKey, Object source) { 129 int localSize = dependencyStackSize; 130 Object[] localStack = dependencyStack; 131 if (localStack.length < localSize + 2) { 132 localStack = dependencyStack = 133 java.util.Arrays.copyOf(localStack, (localStack.length * 3) / 2 + 2); 134 } 135 localStack[localSize++] = dependencyOrKey; 136 localStack[localSize++] = source; 137 dependencyStackSize = localSize; 138 } 139 140 141 /** Pops from the state without setting a dependency. */ popState()142 void popState() { 143 // N.B. we don't null out the array entries. It isn't necessary since all the objects in the 144 // array (Key, Dependency, or Binding source objects) are all tied to the lifetime of the 145 // injector, which is greater than the lifetime of this object. So removing them from the array 146 // doesn't matter. 147 dependencyStackSize -= 2; 148 } 149 150 151 /** Returns the current dependency chain (all the state stored in the dependencyStack). */ getDependencyChain()152 java.util.List<com.google.inject.spi.DependencyAndSource> getDependencyChain() { 153 com.google.common.collect.ImmutableList.Builder<com.google.inject.spi.DependencyAndSource> 154 builder = com.google.common.collect.ImmutableList.builder(); 155 for (int i = 0; i < dependencyStackSize; i += 2) { 156 Object evenEntry = dependencyStack[i]; 157 Dependency<?> dependency; 158 if (evenEntry instanceof com.google.inject.Key) { 159 dependency = Dependency.get((com.google.inject.Key<?>) evenEntry); 160 } else { 161 dependency = (Dependency<?>) evenEntry; 162 } 163 builder.add(new com.google.inject.spi.DependencyAndSource(dependency, dependencyStack[i + 1])); 164 } 165 return builder.build(); 166 } 167 168 } 169