Allow overriding the config key used to configure a cache

This will allow us to tie the size of one cache to match the size of
another cache.

Change-Id: I6e2fa78db8aec209fdc71ace74c28778c8192675

java/com/google/gerrit/server/cache/CacheBinding.java

@@ -37,8 +37,30 @@ public interface CacheBinding<K, V> {
   /** Algorithm to weigh an object with a method other than the unit weight 1. */
   CacheBinding<K, V> weigher(Class<? extends Weigher<K, V>> clazz);
 
+  /**
+   * Set the config name to something other than the cache name.
+   *
+   * @see #configKey()
+   */
+  CacheBinding<K, V> configKey(String configKey);
+
+  /**
+   * Unique name for this cache.
+   *
+   * <p>The name can be used in a binding annotation {@code @Named(name)} to inject the cache
+   * configured with this binding.
+   */
   String name();
 
+  /**
+   * Key to use when looking up configuration for this cache.
+   *
+   * <p>Typically, this will match the result of {@link #name()}, so that configuration is keyed by
+   * the actual cache name. However, it may be changed, for example to reuse the size limits of some
+   * other cache.
+   */
+  String configKey();
+
   TypeLiteral<K> keyType();
 
   TypeLiteral<V> valueType();

java/com/google/gerrit/server/cache/CacheProvider.java

@@ -33,6 +33,7 @@ class CacheProvider<K, V> implements Provider<Cache<K, V>>, CacheBinding<K, V> {
   final String name;
   private final TypeLiteral<K> keyType;
   private final TypeLiteral<V> valType;
+  private String configKey;
   private boolean persist;
   private long maximumWeight;
   private long diskLimit;
@@ -109,6 +110,13 @@ class CacheProvider<K, V> implements Provider<Cache<K, V>>, CacheBinding<K, V> {
     return this;
   }
 
+  @Override
+  public CacheBinding<K, V> configKey(String name) {
+    Preconditions.checkState(!frozen, "binding frozen, cannot be modified");
+    configKey = Preconditions.checkNotNull(name);
+    return this;
+  }
+
   @Override
   public String name() {
     if (!Strings.isNullOrEmpty(plugin)) {
@@ -117,6 +125,11 @@ class CacheProvider<K, V> implements Provider<Cache<K, V>>, CacheBinding<K, V> {
     return name;
   }
 
+  @Override
+  public String configKey() {
+    return configKey != null ? configKey : name();
+  }
+
   @Override
   public TypeLiteral<K> keyType() {
     return keyType;

java/com/google/gerrit/server/cache/h2/H2CacheBindingProxy.java

@@ -60,6 +60,11 @@ class H2CacheBindingProxy<K, V> implements CacheBinding<K, V> {
     return source.name();
   }
 
+  @Override
+  public String configKey() {
+    return source.configKey();
+  }
+
   @Override
   public TypeLiteral<K> keyType() {
     return source.keyType();
@@ -85,6 +90,11 @@ class H2CacheBindingProxy<K, V> implements CacheBinding<K, V> {
     return source.loader();
   }
 
+  @Override
+  public CacheBinding<K, V> configKey(String configKey) {
+    throw new RuntimeException(MSG_NOT_SUPPORTED);
+  }
+
   @Override
   public CacheBinding<K, V> maximumWeight(long weight) {
     throw new RuntimeException(MSG_NOT_SUPPORTED);

java/com/google/gerrit/server/cache/h2/H2CacheFactory.java

@@ -155,7 +155,7 @@ class H2CacheFactory implements PersistentCacheFactory, LifecycleListener {
   @SuppressWarnings({"unchecked"})
   @Override
   public <K, V> Cache<K, V> build(CacheBinding<K, V> in) {
-    long limit = config.getLong("cache", in.name(), "diskLimit", in.diskLimit());
+    long limit = config.getLong("cache", in.configKey(), "diskLimit", in.diskLimit());
 
     if (cacheDir == null || limit <= 0) {
       return memCacheFactory.build(in);
@@ -176,7 +176,7 @@ class H2CacheFactory implements PersistentCacheFactory, LifecycleListener {
   @SuppressWarnings("unchecked")
   @Override
   public <K, V> LoadingCache<K, V> build(CacheBinding<K, V> in, CacheLoader<K, V> loader) {
-    long limit = config.getLong("cache", in.name(), "diskLimit", in.diskLimit());
+    long limit = config.getLong("cache", in.configKey(), "diskLimit", in.diskLimit());
 
     if (cacheDir == null || limit <= 0) {
       return memCacheFactory.build(in, loader);

java/com/google/gerrit/server/cache/mem/DefaultMemoryCacheFactory.java

@@ -55,7 +55,8 @@ class DefaultMemoryCacheFactory implements MemoryCacheFactory {
   private <K, V> CacheBuilder<K, V> create(CacheBinding<K, V> def) {
     CacheBuilder<K, V> builder = newCacheBuilder();
     builder.recordStats();
-    builder.maximumWeight(cfg.getLong("cache", def.name(), "memoryLimit", def.maximumWeight()));
+    builder.maximumWeight(
+        cfg.getLong("cache", def.configKey(), "memoryLimit", def.maximumWeight()));
 
     builder = builder.removalListener(forwardingRemovalListenerFactory.create(def.name()));
 
@@ -66,10 +67,10 @@ class DefaultMemoryCacheFactory implements MemoryCacheFactory {
     builder.weigher(weigher);
 
     Long age = def.expireAfterWrite(TimeUnit.SECONDS);
-    if (has(def.name(), "maxAge")) {
+    if (has(def.configKey(), "maxAge")) {
       builder.expireAfterWrite(
           ConfigUtil.getTimeUnit(
-              cfg, "cache", def.name(), "maxAge", age != null ? age : 0, TimeUnit.SECONDS),
+              cfg, "cache", def.configKey(), "maxAge", age != null ? age : 0, TimeUnit.SECONDS),
           TimeUnit.SECONDS);
     } else if (age != null) {
       builder.expireAfterWrite(age, TimeUnit.SECONDS);