Implement QuotaTemporaryStorageEvictor.

webkit/quota/quota_temporary_storage_evictor.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "webkit/quota/quota_temporary_storage_evictor.h"
+
+#include "googleurl/src/gurl.h"
+
+namespace quota {
+
+const double QuotaTemporaryStorageEvictor::kUsageRatioToStartEviction = 0.7;
+const int64 QuotaTemporaryStorageEvictor::
+    kDefaultMinAvailableDiskSpaceToStartEviction = 1000 * 1000 * 500;
+
+QuotaTemporaryStorageEvictor::QuotaTemporaryStorageEvictor(
+    QuotaEvictionHandler* quota_eviction_handler,
+    int64 interval_ms,
+    scoped_refptr<base::MessageLoopProxy> io_thread)
+    : min_available_disk_space_to_start_eviction_(
+          kDefaultMinAvailableDiskSpaceToStartEviction),
+      quota_eviction_handler_(quota_eviction_handler),
+      interval_ms_(interval_ms),
+      repeated_eviction_(false),
+      io_thread_(io_thread),
+      callback_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+  DCHECK(quota_eviction_handler);
+}
+
+QuotaTemporaryStorageEvictor::~QuotaTemporaryStorageEvictor() {
+}
+
+void QuotaTemporaryStorageEvictor::Start() {
+  DCHECK(io_thread_->BelongsToCurrentThread());
+  StartEvictionTimerWithDelay(0);
+}
+
+void QuotaTemporaryStorageEvictor::StartEvictionTimerWithDelay(int delay_ms) {
+  if (timer_.IsRunning())
+    return;
+  timer_.Start(base::TimeDelta::FromMilliseconds(delay_ms), this,
+               &QuotaTemporaryStorageEvictor::ConsiderEviction);
+}
+
+void QuotaTemporaryStorageEvictor::ConsiderEviction() {
+  // Get usage and disk space, then continue.
+  quota_eviction_handler_->GetUsageAndQuotaForEviction(callback_factory_.
+      NewCallback(
+          &QuotaTemporaryStorageEvictor::OnGotUsageAndQuotaForEviction));
+}
+
+void QuotaTemporaryStorageEvictor::OnGotUsageAndQuotaForEviction(
+    QuotaStatusCode status,
+    int64 usage,
+    int64 quota,
+    int64 available_disk_space) {
+  DCHECK(io_thread_->BelongsToCurrentThread());
+
+  if (status == kQuotaStatusOk &&
+      (usage > quota * kUsageRatioToStartEviction ||
+       min_available_disk_space_to_start_eviction_ > available_disk_space)) {
+    // Space is getting tight. Get the least recently used origin and continue.
+    quota_eviction_handler_->GetLRUOrigin(kStorageTypeTemporary,
+        callback_factory_.NewCallback(
+            &QuotaTemporaryStorageEvictor::OnGotLRUOrigin));
+  } else if (repeated_eviction_) {
+    // No action required, sleep for a while check again later.

[kinuko, 2011/05/24 09:20:53]

nit: 'and' before 'check' (... sleep for a while *and* check again...)

[Dai Mikurube (NOT FULLTIME), 2011/05/24 11:30:52]

Done.

+    StartEvictionTimerWithDelay(interval_ms_);
+  }

[kinuko, 2011/05/24 09:20:53]

Maybe we should have a TODO comment about error case handling here?

(At least we'll really want to have some simple Stats struct (or variables) to
hold several statistics variables: like # of errors, # of eviction, # of
skipped-evictions (i.e. how many times GetLRUOrigin returned empty origin),
current origin which is being evicted, origins that have repeated errors
(nice-to-have) etc.
Otherwise debugging or diagnosing what's happening on a bug report will be
extremely difficult.)

[Dai Mikurube (NOT FULLTIME), 2011/05/24 11:30:52]

For now, added two TODO comments for stats and error handling.

I'll make a change list for stats soon.

+}
+
+void QuotaTemporaryStorageEvictor::OnGotLRUOrigin(const GURL& origin) {
+  DCHECK(io_thread_->BelongsToCurrentThread());
+
+  if (origin.is_empty()) {
+    if (repeated_eviction_)
+      StartEvictionTimerWithDelay(interval_ms_);
+    return;
+  }
+
+  quota_eviction_handler_->EvictOriginData(origin, kStorageTypeTemporary,
+      callback_factory_.NewCallback(
+          &QuotaTemporaryStorageEvictor::OnEvictionComplete));
+}
+
+void QuotaTemporaryStorageEvictor::OnEvictionComplete(
+    QuotaStatusCode status) {
+  DCHECK(io_thread_->BelongsToCurrentThread());
+
+  // We many need to get rid of more space so reconsider immediately.
+  ConsiderEviction();
+}
+
+}  // namespace quota