1 files changed, 117 insertions, 0 deletions
diff --git a/xpcom/base/RLBoxSandboxPool.cpp b/xpcom/base/RLBoxSandboxPool.cpp
new file mode 100644
index 0000000000..5cee3406ea
--- /dev/null
+++ b/xpcom/base/RLBoxSandboxPool.cpp
@@ -0,0 +1,117 @@
+/* -*- 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 "nsThreadUtils.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/RLBoxSandboxPool.h"
+#ifdef MOZ_USING_WASM_SANDBOXING
+#  include "mozilla/rlbox/rlbox_config.h"
+#  include "mozilla/rlbox/rlbox_wasm2c_sandbox.hpp"
+#endif
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(RLBoxSandboxPool, nsITimerCallback, nsINamed)
+
+void RLBoxSandboxPool::StartTimer() {
+  mMutex.AssertCurrentThreadOwns();
+  MOZ_ASSERT(!mTimer, "timer already initialized");
+  if (NS_IsMainThread() &&
+      PastShutdownPhase(ShutdownPhase::AppShutdownConfirmed)) {
+    // If we're shutting down, setting the time might fail, and we don't need it
+    // (since all the memory will be cleaned up soon anyway). Note that
+    // PastShutdownPhase() can only be called on the main thread, but that's
+    // fine, because other threads will have joined already by the point timers
+    // start failing to register.
+    mPool.Clear();
+    return;
+  }
+  DebugOnly<nsresult> rv = NS_NewTimerWithCallback(
+      getter_AddRefs(mTimer), this, mDelaySeconds * 1000,
+      nsITimer::TYPE_ONE_SHOT, GetMainThreadEventTarget());
+  MOZ_ASSERT(NS_SUCCEEDED(rv), "failed to create timer");
+}
+
+void RLBoxSandboxPool::CancelTimer() {
+  mMutex.AssertCurrentThreadOwns();
+  if (mTimer) {
+    mTimer->Cancel();
+    mTimer = nullptr;
+  }
+}
+
+NS_IMETHODIMP RLBoxSandboxPool::Notify(nsITimer* aTimer) {
+  MutexAutoLock lock(mMutex);
+
+  mPool.Clear();
+  mTimer = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP RLBoxSandboxPool::GetName(nsACString& aName) {
+  aName.AssignLiteral("RLBoxSandboxPool");
+  return NS_OK;
+}
+
+void RLBoxSandboxPool::Push(UniquePtr<RLBoxSandboxDataBase> sbxData) {
+  MutexAutoLock lock(mMutex);
+
+  mPool.AppendElement(std::move(sbxData));
+  if (!mTimer) {
+    StartTimer();
+  }
+}
+
+UniquePtr<RLBoxSandboxPoolData> RLBoxSandboxPool::PopOrCreate(
+    uint64_t aMinSize) {
+  MutexAutoLock lock(mMutex);
+
+  UniquePtr<RLBoxSandboxDataBase> sbxData;
+
+  if (!mPool.IsEmpty()) {
+    const int64_t lastIndex = ReleaseAssertedCast<int64_t>(mPool.Length()) - 1;
+    for (int64_t i = lastIndex; i >= 0; i--) {
+      if (mPool[i]->mSize >= aMinSize) {
+        sbxData = std::move(mPool[i]);
+        mPool.RemoveElementAt(i);
+
+        // If we reuse a sandbox from the pool, reset the timer to clear the
+        // pool
+        CancelTimer();
+        if (!mPool.IsEmpty()) {
+          StartTimer();
+        }
+        break;
+      }
+    }
+  }
+
+  if (!sbxData) {
+#ifdef MOZ_USING_WASM_SANDBOXING
+    // RLBox's wasm sandboxes have a limited platform dependent capacity. We
+    // track this capacity in this pool. Note the noop sandboxes have no
+    // capacity limit but this design assumes that all sandboxes use the wasm
+    // sandbox limit.
+    const uint64_t defaultCapacityForSandbox =
+        wasm_rt_get_default_max_linear_memory_size();
+    const uint64_t minSandboxCapacity =
+        std::max(aMinSize, defaultCapacityForSandbox);
+    const uint64_t chosenAdjustedCapacity =
+        rlbox::rlbox_wasm2c_sandbox::rlbox_wasm2c_get_adjusted_heap_size(
+            minSandboxCapacity);
+#else
+    // If sandboxing is disabled altogether we just set a limit of 4gb.
+    // This is not actually enforced by the noop sandbox.
+    const uint64_t chosenAdjustedCapacity = static_cast<uint64_t>(1) << 32;
+#endif
+    sbxData = CreateSandboxData(chosenAdjustedCapacity);
+    NS_ENSURE_TRUE(sbxData, nullptr);
+  }
+
+  return MakeUnique<RLBoxSandboxPoolData>(std::move(sbxData), this);
+}