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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/viz/common/surfaces/child_local_surface_id_allocator.h"
#include "base/rand_util.h"
#include "base/time/default_tick_clock.h"
#include "base/trace_event/trace_event.h"
namespace viz {
ChildLocalSurfaceIdAllocator::ChildLocalSurfaceIdAllocator()
: current_local_surface_id_(kInvalidParentSequenceNumber,
kInitialChildSequenceNumber,
base::UnguessableToken()) {}
bool ChildLocalSurfaceIdAllocator::UpdateFromParent(
const LocalSurfaceId& parent_local_surface_id) {
const LocalSurfaceId& current_local_surface_id = current_local_surface_id_;
const LocalSurfaceId& parent_allocated_local_surface_id =
parent_local_surface_id;
// If the parent has not incremented its parent sequence number or updated its
// embed token then there is nothing to do here. This allocator already has
// the latest LocalSurfaceId.
if (current_local_surface_id.parent_sequence_number() >=
parent_allocated_local_surface_id.parent_sequence_number() &&
current_local_surface_id.embed_token() ==
parent_allocated_local_surface_id.embed_token()) {
return false;
}
if (current_local_surface_id.child_sequence_number() >
parent_allocated_local_surface_id.child_sequence_number()) {
// If the current LocalSurfaceId has a newer child sequence number
// than the one provided by the parent, then the merged LocalSurfaceId
// is actually a new LocalSurfaceId and so we report its allocation time
// as now.
if (current_local_surface_id != parent_allocated_local_surface_id) {
TRACE_EVENT_WITH_FLOW2(
TRACE_DISABLED_BY_DEFAULT("viz.surface_id_flow"),
"ChildLocalSurfaceIdAllocator::UpdateFromParent New Id Allocation",
TRACE_ID_LOCAL(
parent_allocated_local_surface_id.submission_trace_id()),
TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT, "current",
current_local_surface_id_.ToString(), "parent",
parent_local_surface_id.ToString());
}
} else if (current_local_surface_id != parent_allocated_local_surface_id) {
TRACE_EVENT_WITH_FLOW2(
TRACE_DISABLED_BY_DEFAULT("viz.surface_id_flow"),
"ChildLocalSurfaceIdAllocator::UpdateFromParent Synchronization",
TRACE_ID_LOCAL(parent_allocated_local_surface_id.submission_trace_id()),
TRACE_EVENT_FLAG_FLOW_IN | TRACE_EVENT_FLAG_FLOW_OUT, "current",
current_local_surface_id_.ToString(), "parent",
parent_local_surface_id.ToString());
}
// If embed token has changed, accept all fields from the parent
// including child sequence number.
if (current_local_surface_id.embed_token() !=
parent_allocated_local_surface_id.embed_token()) {
current_local_surface_id_.child_sequence_number_ =
parent_allocated_local_surface_id.child_sequence_number_;
}
current_local_surface_id_.parent_sequence_number_ =
parent_allocated_local_surface_id.parent_sequence_number_;
current_local_surface_id_.embed_token_ =
parent_allocated_local_surface_id.embed_token_;
return true;
}
void ChildLocalSurfaceIdAllocator::GenerateId() {
// UpdateFromParent must be called before we can generate a valid ID.
DCHECK_NE(current_local_surface_id_.parent_sequence_number(),
kInvalidParentSequenceNumber);
++current_local_surface_id_.child_sequence_number_;
TRACE_EVENT_WITH_FLOW2(
TRACE_DISABLED_BY_DEFAULT("viz.surface_id_flow"),
"LocalSurfaceId.Embed.Flow",
TRACE_ID_GLOBAL(current_local_surface_id_.embed_trace_id()),
TRACE_EVENT_FLAG_FLOW_OUT, "step",
"ChildLocalSurfaceIdAllocator::GenerateId", "local_surface_id",
current_local_surface_id_.ToString());
TRACE_EVENT_WITH_FLOW2(
TRACE_DISABLED_BY_DEFAULT("viz.surface_id_flow"),
"LocalSurfaceId.Submission.Flow",
TRACE_ID_GLOBAL(current_local_surface_id_.submission_trace_id()),
TRACE_EVENT_FLAG_FLOW_OUT, "step",
"ChildLocalSurfaceIdAllocator::GenerateId", "local_surface_id",
current_local_surface_id_.ToString());
}
} // namespace viz
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