Merge "Make H2 database cache size configurable"

Documentation/config-gerrit.txt

@@ -528,6 +528,20 @@ If not absolute, the path is resolved relative to `$site_path`.
 +
 Default is unset, no disk cache.
 
+[[cache.h2CacheSize]]cache.h2CacheSize::
++
+The size of the H2 database cache, in bytes, used for each persistent cache.
+This can be used to limit the H2 cache size and thus prevent out-of-memory
+caused by the H2 database using too much memory.
++
+Technically the H2 cache size is configured using the CACHE_SIZE parameter in
+the H2 JDBC connection URL, as described
+link:http://www.h2database.com/html/features.html#cache_settings[here]
++
+Default is unset, no cache size limit.
++
+Common unit suffixes of 'k', 'm', or 'g' are supported.
+
 [[cache.name.maxAge]]cache.<name>.maxAge::
 +
 Maximum age to keep an entry in the cache. Entries are removed from

gerrit-cache-h2/src/main/java/com/google/gerrit/server/cache/h2/H2CacheFactory.java

@@ -58,6 +58,7 @@ class H2CacheFactory implements PersistentCacheFactory, LifecycleListener {
   private final DynamicMap<Cache<?, ?>> cacheMap;
   private final ExecutorService executor;
   private final ScheduledExecutorService cleanup;
+  private final long h2CacheSize;
 
   @Inject
   H2CacheFactory(
@@ -68,6 +69,7 @@ class H2CacheFactory implements PersistentCacheFactory, LifecycleListener {
     defaultFactory = defaultCacheFactory;
     config = cfg;
     cacheDir = getCacheDir(site, cfg.getString("cache", null, "directory"));
+    h2CacheSize = cfg.getLong("cache", null, "h2CacheSize", -1);
     caches = Lists.newLinkedList();
     this.cacheMap = cacheMap;
 
@@ -220,8 +222,14 @@ class H2CacheFactory implements PersistentCacheFactory, LifecycleListener {
       TypeLiteral<K> keyType,
       long maxSize,
       Long expireAfterWrite) {
-    String url = "jdbc:h2:" + cacheDir.resolve(name).toUri();
-    return new SqlStore<>(url, keyType, maxSize,
+    StringBuilder url = new StringBuilder();
+    url.append("jdbc:h2:").append(cacheDir.resolve(name).toUri());
+    if (h2CacheSize >= 0) {
+      url.append(";CACHE_SIZE=");
+      // H2 CACHE_SIZE is always given in KB
+      url.append(h2CacheSize / 1024);
+    }
+    return new SqlStore<>(url.toString(), keyType, maxSize,
         expireAfterWrite == null ? 0 : expireAfterWrite.longValue());
   }
 }