1 files changed, 317 insertions, 0 deletions
diff --git a/cc/scheduler_state_machine.cc b/cc/scheduler_state_machine.cc
new file mode 100644
index 0000000..3eaf5cd
--- /dev/null
+++ b/cc/scheduler_state_machine.cc
@@ -0,0 +1,317 @@
+// Copyright 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 "config.h"
+
+#include "CCSchedulerStateMachine.h"
+#include "base/stringprintf.h"
+
+
+namespace cc {
+
+CCSchedulerStateMachine::CCSchedulerStateMachine()
+    : m_commitState(COMMIT_STATE_IDLE)
+    , m_currentFrameNumber(0)
+    , m_lastFrameNumberWhereDrawWasCalled(-1)
+    , m_consecutiveFailedDraws(0)
+    , m_maximumNumberOfFailedDrawsBeforeDrawIsForced(3)
+    , m_needsRedraw(false)
+    , m_needsForcedRedraw(false)
+    , m_needsForcedRedrawAfterNextCommit(false)
+    , m_needsCommit(false)
+    , m_needsForcedCommit(false)
+    , m_mainThreadNeedsLayerTextures(false)
+    , m_insideVSync(false)
+    , m_visible(false)
+    , m_canBeginFrame(false)
+    , m_canDraw(false)
+    , m_drawIfPossibleFailed(false)
+    , m_textureState(LAYER_TEXTURE_STATE_UNLOCKED)
+    , m_contextState(CONTEXT_ACTIVE)
+{
+}
+
+std::string CCSchedulerStateMachine::toString()
+{
+    std::string str;
+    base::StringAppendF(&str, "m_commitState = %d; ", m_commitState);
+    base::StringAppendF(&str, "m_currentFrameNumber = %d; ", m_currentFrameNumber);
+    base::StringAppendF(&str, "m_lastFrameNumberWhereDrawWasCalled = %d; ", m_lastFrameNumberWhereDrawWasCalled);
+    base::StringAppendF(&str, "m_consecutiveFailedDraws = %d; ", m_consecutiveFailedDraws);
+    base::StringAppendF(&str, "m_maximumNumberOfFailedDrawsBeforeDrawIsForced = %d; ", m_maximumNumberOfFailedDrawsBeforeDrawIsForced);
+    base::StringAppendF(&str, "m_needsRedraw = %d; ", m_needsRedraw);
+    base::StringAppendF(&str, "m_needsForcedRedraw = %d; ", m_needsForcedRedraw);
+    base::StringAppendF(&str, "m_needsForcedRedrawAfterNextCommit = %d; ", m_needsForcedRedrawAfterNextCommit);
+    base::StringAppendF(&str, "m_needsCommit = %d; ", m_needsCommit);
+    base::StringAppendF(&str, "m_needsForcedCommit = %d; ", m_needsForcedCommit);
+    base::StringAppendF(&str, "m_mainThreadNeedsLayerTextures = %d; ", m_mainThreadNeedsLayerTextures);
+    base::StringAppendF(&str, "m_insideVSync = %d; ", m_insideVSync);
+    base::StringAppendF(&str, "m_visible = %d; ", m_visible);
+    base::StringAppendF(&str, "m_canBeginFrame = %d; ", m_canBeginFrame);
+    base::StringAppendF(&str, "m_canDraw = %d; ", m_canDraw);
+    base::StringAppendF(&str, "m_drawIfPossibleFailed = %d; ", m_drawIfPossibleFailed);
+    base::StringAppendF(&str, "m_textureState = %d; ", m_textureState);
+    base::StringAppendF(&str, "m_contextState = %d; ", m_contextState);
+    return str;
+}
+
+bool CCSchedulerStateMachine::hasDrawnThisFrame() const
+{
+    return m_currentFrameNumber == m_lastFrameNumberWhereDrawWasCalled;
+}
+
+bool CCSchedulerStateMachine::drawSuspendedUntilCommit() const
+{
+    if (!m_canDraw)
+        return true;
+    if (!m_visible)
+        return true;
+    if (m_textureState == LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD)
+        return true;
+    return false;
+}
+
+bool CCSchedulerStateMachine::scheduledToDraw() const
+{
+    if (!m_needsRedraw)
+        return false;
+    if (drawSuspendedUntilCommit())
+        return false;
+    return true;
+}
+
+bool CCSchedulerStateMachine::shouldDraw() const
+{
+    if (m_needsForcedRedraw)
+        return true;
+
+    if (!scheduledToDraw())
+        return false;
+    if (!m_insideVSync)
+        return false;
+    if (hasDrawnThisFrame())
+        return false;
+    if (m_contextState != CONTEXT_ACTIVE)
+        return false;
+    return true;
+}
+
+bool CCSchedulerStateMachine::shouldAcquireLayerTexturesForMainThread() const
+{
+    if (!m_mainThreadNeedsLayerTextures)
+        return false;
+    if (m_textureState == LAYER_TEXTURE_STATE_UNLOCKED)
+        return true;
+    ASSERT(m_textureState == LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD);
+    // Transfer the lock from impl thread to main thread immediately if the
+    // impl thread is not even scheduled to draw. Guards against deadlocking.
+    if (!scheduledToDraw())
+        return true;
+    if (!vsyncCallbackNeeded())
+        return true;
+    return false;
+}
+
+CCSchedulerStateMachine::Action CCSchedulerStateMachine::nextAction() const
+{
+    if (shouldAcquireLayerTexturesForMainThread())
+        return ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD;
+    switch (m_commitState) {
+    case COMMIT_STATE_IDLE:
+        if (m_contextState != CONTEXT_ACTIVE && m_needsForcedRedraw)
+            return ACTION_DRAW_FORCED;
+        if (m_contextState != CONTEXT_ACTIVE && m_needsForcedCommit)
+            return ACTION_BEGIN_FRAME;
+        if (m_contextState == CONTEXT_LOST)
+            return ACTION_BEGIN_CONTEXT_RECREATION;
+        if (m_contextState == CONTEXT_RECREATING)
+            return ACTION_NONE;
+        if (shouldDraw())
+            return m_needsForcedRedraw ? ACTION_DRAW_FORCED : ACTION_DRAW_IF_POSSIBLE;
+        if (m_needsCommit && ((m_visible && m_canBeginFrame) || m_needsForcedCommit))
+            return ACTION_BEGIN_FRAME;
+        return ACTION_NONE;
+
+    case COMMIT_STATE_FRAME_IN_PROGRESS:
+        if (shouldDraw())
+            return m_needsForcedRedraw ? ACTION_DRAW_FORCED : ACTION_DRAW_IF_POSSIBLE;
+        return ACTION_NONE;
+
+    case COMMIT_STATE_READY_TO_COMMIT:
+        return ACTION_COMMIT;
+
+    case COMMIT_STATE_WAITING_FOR_FIRST_DRAW:
+        if (shouldDraw() || m_contextState == CONTEXT_LOST)
+            return m_needsForcedRedraw ? ACTION_DRAW_FORCED : ACTION_DRAW_IF_POSSIBLE;
+        // COMMIT_STATE_WAITING_FOR_FIRST_DRAW wants to enforce a draw. If m_canDraw is false
+        // or textures are not available, proceed to the next step (similar as in COMMIT_STATE_IDLE).
+        bool canCommit = m_visible || m_needsForcedCommit;
+        if (m_needsCommit && canCommit && drawSuspendedUntilCommit())
+            return ACTION_BEGIN_FRAME;
+        return ACTION_NONE;
+    }
+    ASSERT_NOT_REACHED();
+    return ACTION_NONE;
+}
+
+void CCSchedulerStateMachine::updateState(Action action)
+{
+    switch (action) {
+    case ACTION_NONE:
+        return;
+
+    case ACTION_BEGIN_FRAME:
+        ASSERT(m_visible || m_needsForcedCommit);
+        m_commitState = COMMIT_STATE_FRAME_IN_PROGRESS;
+        m_needsCommit = false;
+        m_needsForcedCommit = false;
+        return;
+
+    case ACTION_COMMIT:
+        m_commitState = COMMIT_STATE_WAITING_FOR_FIRST_DRAW;
+        m_needsRedraw = true;
+        if (m_drawIfPossibleFailed)
+            m_lastFrameNumberWhereDrawWasCalled = -1;
+
+        if (m_needsForcedRedrawAfterNextCommit) {
+            m_needsForcedRedrawAfterNextCommit = false;
+            m_needsForcedRedraw = true;
+        }
+
+        m_textureState = LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD;
+        return;
+
+    case ACTION_DRAW_FORCED:
+    case ACTION_DRAW_IF_POSSIBLE:
+        m_needsRedraw = false;
+        m_needsForcedRedraw = false;
+        m_drawIfPossibleFailed = false;
+        if (m_insideVSync)
+            m_lastFrameNumberWhereDrawWasCalled = m_currentFrameNumber;
+        if (m_commitState == COMMIT_STATE_WAITING_FOR_FIRST_DRAW)
+            m_commitState = COMMIT_STATE_IDLE;
+        if (m_textureState == LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD)
+            m_textureState = LAYER_TEXTURE_STATE_UNLOCKED;
+        return;
+
+    case ACTION_BEGIN_CONTEXT_RECREATION:
+        ASSERT(m_commitState == COMMIT_STATE_IDLE);
+        ASSERT(m_contextState == CONTEXT_LOST);
+        m_contextState = CONTEXT_RECREATING;
+        return;
+
+    case ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD:
+        m_textureState = LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD;
+        m_mainThreadNeedsLayerTextures = false;
+        if (m_commitState != COMMIT_STATE_FRAME_IN_PROGRESS)
+            m_needsCommit = true;
+        return;
+    }
+}
+
+void CCSchedulerStateMachine::setMainThreadNeedsLayerTextures()
+{
+    ASSERT(!m_mainThreadNeedsLayerTextures);
+    ASSERT(m_textureState != LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD);
+    m_mainThreadNeedsLayerTextures = true;
+}
+
+bool CCSchedulerStateMachine::vsyncCallbackNeeded() const
+{
+    // If we can't draw, don't tick until we are notified that we can draw again.
+    if (!m_canDraw)
+        return false;
+
+    if (m_needsForcedRedraw)
+        return true;
+
+    return m_needsRedraw && m_visible && m_contextState == CONTEXT_ACTIVE;
+}
+
+void CCSchedulerStateMachine::didEnterVSync()
+{
+    m_insideVSync = true;
+}
+
+void CCSchedulerStateMachine::didLeaveVSync()
+{
+    m_currentFrameNumber++;
+    m_insideVSync = false;
+}
+
+void CCSchedulerStateMachine::setVisible(bool visible)
+{
+    m_visible = visible;
+}
+
+void CCSchedulerStateMachine::setNeedsRedraw()
+{
+    m_needsRedraw = true;
+}
+
+void CCSchedulerStateMachine::setNeedsForcedRedraw()
+{
+    m_needsForcedRedraw = true;
+}
+
+void CCSchedulerStateMachine::didDrawIfPossibleCompleted(bool success)
+{
+    m_drawIfPossibleFailed = !success;
+    if (m_drawIfPossibleFailed) {
+        m_needsRedraw = true;
+        m_needsCommit = true;
+        m_consecutiveFailedDraws++;
+        if (m_consecutiveFailedDraws >= m_maximumNumberOfFailedDrawsBeforeDrawIsForced) {
+            m_consecutiveFailedDraws = 0;
+            // We need to force a draw, but it doesn't make sense to do this until
+            // we've committed and have new textures.
+            m_needsForcedRedrawAfterNextCommit = true;
+        }
+    } else
+      m_consecutiveFailedDraws = 0;
+}
+
+void CCSchedulerStateMachine::setNeedsCommit()
+{
+    m_needsCommit = true;
+}
+
+void CCSchedulerStateMachine::setNeedsForcedCommit()
+{
+    m_needsForcedCommit = true;
+}
+
+void CCSchedulerStateMachine::beginFrameComplete()
+{
+    ASSERT(m_commitState == COMMIT_STATE_FRAME_IN_PROGRESS);
+    m_commitState = COMMIT_STATE_READY_TO_COMMIT;
+}
+
+void CCSchedulerStateMachine::beginFrameAborted()
+{
+    ASSERT(m_commitState == COMMIT_STATE_FRAME_IN_PROGRESS);
+    m_commitState = COMMIT_STATE_IDLE;
+    setNeedsCommit();
+}
+
+void CCSchedulerStateMachine::didLoseContext()
+{
+    if (m_contextState == CONTEXT_LOST || m_contextState == CONTEXT_RECREATING)
+        return;
+    m_contextState = CONTEXT_LOST;
+}
+
+void CCSchedulerStateMachine::didRecreateContext()
+{
+    ASSERT(m_contextState == CONTEXT_RECREATING);
+    m_contextState = CONTEXT_ACTIVE;
+    setNeedsCommit();
+}
+
+void CCSchedulerStateMachine::setMaximumNumberOfFailedDrawsBeforeDrawIsForced(int numDraws)
+{
+    m_maximumNumberOfFailedDrawsBeforeDrawIsForced = numDraws;
+}
+
+}