1 files changed, 67 insertions, 0 deletions
diff --git a/js/src/vm/StencilCache.cpp b/js/src/vm/StencilCache.cpp
new file mode 100644
index 0000000000..8483d44300
--- /dev/null
+++ b/js/src/vm/StencilCache.cpp
@@ -0,0 +1,67 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "vm/StencilCache.h"
+
+#include "frontend/CompilationStencil.h"
+#include "js/experimental/JSStencil.h"
+#include "vm/MutexIDs.h"
+
+js::StencilCache::StencilCache()
+    : cache(js::mutexid::StencilCache), enabled(false) {}
+
+js::StencilCache::AccessKey js::StencilCache::isSourceCached(
+    ScriptSource* src) {
+  if (!enabled) {
+    return cache.noAccess();
+  }
+
+  AccessKey lock(cache.lock());
+  if (!enabled) {
+    // As we checked the flag before taking the lock, we have to check again to
+    // avoid races on the cache manipulation.
+    return cache.noAccess();
+  }
+  if (!lock->watched.has(src)) {
+    // If the source does not have any cached function, and we do not expect to
+    // cache any delazification in the future, then skip any cache handling.
+    return cache.noAccess();
+  }
+  return lock;
+}
+
+bool js::StencilCache::startCaching(RefPtr<ScriptSource>&& src) {
+  auto guard = cache.lock();
+  if (!guard->watched.putNew(std::move(src))) {
+    return false;
+  }
+  enabled = true;
+  return true;
+}
+
+js::frontend::CompilationStencil* js::StencilCache::lookup(
+    AccessKey& guard, const StencilContext& key) {
+  auto ptr = guard->functions.lookup(key);
+  if (!ptr) {
+    return nullptr;
+  }
+
+  return ptr->value().get();
+}
+
+bool js::StencilCache::putNew(AccessKey& guard, const StencilContext& key,
+                              js::frontend::CompilationStencil* value) {
+  return guard->functions.putNew(key, value);
+}
+
+// Important: This function should not be called within a scope checking for
+// isSourceCached, as this would cause a dead-lock.
+void js::StencilCache::clearAndDisable() {
+  auto guard = cache.lock();
+  guard->functions.clearAndCompact();
+  guard->watched.clearAndCompact();
+  enabled = false;
+}