1 files changed, 112 insertions, 0 deletions
diff --git a/src/main/java/com/google/gerrit/client/data/AccountInfoCacheFactory.java b/src/main/java/com/google/gerrit/client/data/AccountInfoCacheFactory.java
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+// Copyright 2008 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.data;
+
+import com.google.gerrit.client.reviewdb.Account;
+import com.google.gerrit.client.reviewdb.ReviewDb;
+import com.google.gerrit.client.rpc.Common;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+
+/** Efficiently builds a {@link AccountInfoCache}. */
+public class AccountInfoCacheFactory {
+  private final ReviewDb db;
+  private final HashMap<Account.Id, Account> cache;
+  private final HashSet<Account.Id> toFetch;
+
+  public AccountInfoCacheFactory(final ReviewDb schema) {
+    db = schema;
+    cache = new HashMap<Account.Id, Account>();
+    toFetch = new HashSet<Account.Id>();
+  }
+
+  /**
+   * Indicate an account will be needed later on.
+   * <p>
+   * This method permits batch fetching from the data store by building a list
+   * of Account.Ids which need to be obtained during the next {@link #fetch}.
+   * 
+   * @param id identity that will be needed in the future; may be null.
+   */
+  public void want(final Account.Id id) {
+    if (id != null && !cache.containsKey(id)) {
+      toFetch.add(id);
+    }
+  }
+
+  /** Indicate one or more accounts will be needed later on. */
+  public void want(final Collection<Account.Id> ids) {
+    for (final Account.Id id : ids) {
+      want(id);
+    }
+  }
+
+  /** Fetch all accounts previously queued by {@link #want(Account.Id)} */
+  public void fetch() {
+    if (!toFetch.isEmpty()) {
+      for (final Account a : Common.getAccountCache().get(toFetch, db)) {
+        cache.put(a.getId(), a);
+      }
+      toFetch.clear();
+    }
+  }
+
+  /** Load one account entity, reusing a cached instance if already loaded. */
+  public Account get(final Account.Id id) {
+    if (id == null) {
+      return null;
+    }
+
+    Account a = cache.get(id);
+    if (a == null) {
+      if (toFetch.isEmpty()) {
+        a = Common.getAccountCache().get(id, db);
+        if (a != null) {
+          cache.put(id, a);
+        }
+      } else {
+        toFetch.add(id);
+        fetch();
+        a = cache.get(id);
+      }
+    }
+    return a;
+  }
+
+  /** Remember one account that was previously loaded. */
+  public void put(final Account a) {
+    toFetch.remove(a.getId());
+    cache.put(a.getId(), a);
+  }
+
+  /**
+   * Create an AccountInfoCache with the currently loaded Account entities.
+   * <p>
+   * Implicitly invokes {@link #fetch()} prior to creating the cache, ensuring
+   * any previously enqueued entities will be included in the result.
+   * */
+  public AccountInfoCache create() {
+    fetch();
+    final List<AccountInfo> r = new ArrayList<AccountInfo>(cache.size());
+    for (final Account a : cache.values()) {
+      r.add(new AccountInfo(a));
+    }
+    return new AccountInfoCache(r);
+  }
+}