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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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
#include "WebGLChild.h"
#include "ClientWebGLContext.h"
#include "mozilla/StaticPrefs_webgl.h"
#include "WebGLMethodDispatcher.h"
namespace mozilla::dom {
WebGLChild::WebGLChild(ClientWebGLContext& context)
: mContext(&context),
mDefaultCmdsShmemSize(StaticPrefs::webgl_out_of_process_shmem_size()) {}
WebGLChild::~WebGLChild() { Destroy(); }
void WebGLChild::Destroy() {
if (!CanSend()) {
return;
}
if (mContext) {
mContext->OnDestroyChild(this);
}
(void)Send__delete__(this);
}
void WebGLChild::ActorDestroy(ActorDestroyReason why) {
mPendingCmdsShmem = {};
}
// -
Maybe<Range<uint8_t>> WebGLChild::AllocPendingCmdBytes(
const size_t size, const size_t fyiAlignmentOverhead) {
if (!mPendingCmdsShmem.Size()) {
size_t capacity = mDefaultCmdsShmemSize;
if (capacity < size) {
capacity = size;
}
mPendingCmdsShmem = mozilla::ipc::BigBuffer::TryAlloc(capacity);
if (!mPendingCmdsShmem.Size()) {
NS_WARNING("Failed to alloc shmem for AllocPendingCmdBytes.");
return {};
}
mPendingCmdsPos = 0;
mPendingCmdsAlignmentOverhead = 0;
if (kIsDebug) {
const auto ptr = mPendingCmdsShmem.Data();
const auto initialOffset = AlignmentOffset(kUniversalAlignment, ptr);
MOZ_ALWAYS_TRUE(!initialOffset);
}
}
const auto range = Range<uint8_t>{mPendingCmdsShmem.AsSpan()};
auto itr = range.begin() + mPendingCmdsPos;
const auto offset = AlignmentOffset(kUniversalAlignment, itr.get());
mPendingCmdsPos += offset;
mPendingCmdsAlignmentOverhead += offset;
const auto required = mPendingCmdsPos + size;
if (required > range.length()) {
FlushPendingCmds();
return AllocPendingCmdBytes(size, fyiAlignmentOverhead);
}
itr = range.begin() + mPendingCmdsPos;
const auto remaining = Range<uint8_t>{itr, range.end()};
mPendingCmdsPos += size;
mPendingCmdsAlignmentOverhead += fyiAlignmentOverhead;
return Some(Range<uint8_t>{remaining.begin(), remaining.begin() + size});
}
void WebGLChild::FlushPendingCmds() {
if (!mPendingCmdsShmem.Size()) return;
const auto byteSize = mPendingCmdsPos;
SendDispatchCommands(std::move(mPendingCmdsShmem), byteSize);
mPendingCmdsShmem = {};
mFlushedCmdInfo.flushes += 1;
mFlushedCmdInfo.flushedCmdBytes += byteSize;
mFlushedCmdInfo.overhead += mPendingCmdsAlignmentOverhead;
// Handle flushesSinceLastCongestionCheck
mFlushedCmdInfo.flushesSinceLastCongestionCheck += 1;
constexpr auto START_CONGESTION_CHECK_THRESHOLD = 20;
constexpr auto ASSUME_IPC_CONGESTION_THRESHOLD = 70;
RefPtr<WebGLChild> self = this;
size_t generation = self->mFlushedCmdInfo.congestionCheckGeneration;
// When ClientWebGLContext uses async remote texture, sync GetFrontBuffer
// message is not sent in ClientWebGLContext::GetFrontBuffer(). It causes a
// case that a lot of async DispatchCommands messages are sent to
// WebGLParent without calling ClientWebGLContext::GetFrontBuffer(). The
// sending DispatchCommands messages could be faster than receiving message
// at WebGLParent by WebGLParent::RecvDispatchCommands(). If it happens,
// pending IPC messages could grow too much until out of resource. To detect
// the messages congestion, async Ping message is used. If the Ping response
// is not received until maybeIPCMessageCongestion, IPC message might be
// congested at WebGLParent. Then sending sync SyncPing flushes all pending
// messages.
// Due to the async nature of the async ping, it is possible for the flush
// check to exceed maybeIPCMessageCongestion, but that it it still bounded.
if (mFlushedCmdInfo.flushesSinceLastCongestionCheck ==
START_CONGESTION_CHECK_THRESHOLD) {
const auto eventTarget = RefPtr{GetCurrentSerialEventTarget()};
MOZ_ASSERT(eventTarget);
if (!eventTarget) {
NS_WARNING("GetCurrentSerialEventTarget()->nullptr in FlushPendingCmds.");
} else {
SendPing()->Then(eventTarget, __func__, [self, generation]() {
if (generation == self->mFlushedCmdInfo.congestionCheckGeneration) {
// Confirmed IPC messages congestion does not happen.
// Reset flushesSinceLastCongestionCheck for next congestion check.
self->mFlushedCmdInfo.flushesSinceLastCongestionCheck = 0;
self->mFlushedCmdInfo.congestionCheckGeneration++;
}
});
}
} else if (mFlushedCmdInfo.flushesSinceLastCongestionCheck >
ASSUME_IPC_CONGESTION_THRESHOLD) {
// IPC messages congestion might happen, send sync SyncPing for flushing
// pending messages.
SendSyncPing();
// Reset flushesSinceLastCongestionCheck for next congestion check.
mFlushedCmdInfo.flushesSinceLastCongestionCheck = 0;
mFlushedCmdInfo.congestionCheckGeneration++;
}
if (gl::GLContext::ShouldSpew()) {
const auto overheadRatio = float(mPendingCmdsAlignmentOverhead) /
(byteSize - mPendingCmdsAlignmentOverhead);
const auto totalOverheadRatio =
float(mFlushedCmdInfo.overhead) /
(mFlushedCmdInfo.flushedCmdBytes - mFlushedCmdInfo.overhead);
printf_stderr(
"[WebGLChild] Flushed %zu (%zu=%.2f%% overhead) bytes."
" (%zu (%.2f%% overhead) over %zu flushes)\n",
byteSize, mPendingCmdsAlignmentOverhead, 100 * overheadRatio,
mFlushedCmdInfo.flushedCmdBytes, 100 * totalOverheadRatio,
mFlushedCmdInfo.flushes);
}
}
// -
mozilla::ipc::IPCResult WebGLChild::RecvJsWarning(
const std::string& text) const {
if (!mContext) return IPC_OK();
mContext->JsWarning(text);
return IPC_OK();
}
mozilla::ipc::IPCResult WebGLChild::RecvOnContextLoss(
const webgl::ContextLossReason reason) const {
if (!mContext) return IPC_OK();
mContext->OnContextLoss(reason);
return IPC_OK();
}
mozilla::ipc::IPCResult WebGLChild::RecvOnSyncComplete(
const webgl::ObjectId id) const {
if (!mContext) return IPC_OK();
mContext->OnSyncComplete(id);
return IPC_OK();
}
} // namespace mozilla::dom