Incrementally flush GrDrawTarget

src/gpu/GrDrawTarget.cpp

Index: src/gpu/GrDrawTarget.cpp
diff --git a/src/gpu/GrDrawTarget.cpp b/src/gpu/GrDrawTarget.cpp
index e7c1c8b5c14a93733bfca40cd8a7b99a82f7b4dd..6cfb985ff21d1ebf6f04e207203d586ea6296b8e 100644
--- a/src/gpu/GrDrawTarget.cpp
+++ b/src/gpu/GrDrawTarget.cpp
@@ -35,8 +35,9 @@
 GrDrawTarget::GrDrawTarget(GrGpu* gpu, GrResourceProvider* resourceProvider)
     : fGpu(SkRef(gpu))
     , fResourceProvider(resourceProvider)
+    , fFlushState(fGpu, fResourceProvider, 0)
     , fFlushing(false)
-    , fLastFlushToken(0) {
+    , fLastPreparedBatch(0) {
     // TODO: Stop extracting the context (currently needed by GrClipMaskManager)
     fContext = fGpu->getContext();
     fClipMaskManager.reset(new GrClipMaskManager(this));
@@ -111,34 +112,40 @@ bool GrDrawTarget::setupDstReadIfNecessary(const GrPipelineBuilder& pipelineBuil
     return true;
 }
 
+void GrDrawTarget::prepareN(int N) {

[bsalomon, 2015/10/02 14:40:17]

I'm wondering how helpful this helper function is, rather than just inlining and
reducing into the two callers. One is just

for (int i = fLastPreparedBatch; i < fBatches.count(); ++i) {
    fBatches[i]->prepare(&fFlushState);
}

and the other is just:

batch->prepare(&fFlushState);
++fLastPreparedBatch;

Also, isn't fLastPreparedBatch really fFirstUnpreparedBatch?

And why is the code that is preparing not also updating fLastPreparedBatch?

+    SkASSERT(fLastPreparedBatch + N <= fBatches.count());
+
+    int flushTo = fLastPreparedBatch + N;
+
+    // Loop over all batches and generate geometry
+    for (int i = fLastPreparedBatch; i < flushTo; ++i) {
+        fBatches[i]->prepare(&fFlushState);
+    }
+}
+
 void GrDrawTarget::flush() {
     if (fFlushing) {
         return;
     }
     fFlushing = true;
 
-    GrBatchFlushState flushState(fGpu, fResourceProvider, fLastFlushToken);
-
-    // Loop over all batches and generate geometry
-    for (int i = 0; i < fBatches.count(); ++i) {
-        fBatches[i]->prepare(&flushState);
-    }
+    this->prepareN(fBatches.count() - fLastPreparedBatch);
 
     // Upload all data to the GPU
-    flushState.preIssueDraws();
+    fFlushState.preIssueDraws();
 
     // Draw all the generated geometry.
     for (int i = 0; i < fBatches.count(); ++i) {
-        fBatches[i]->draw(&flushState);
+        fBatches[i]->draw(&fFlushState);
     }
 
-    fLastFlushToken = flushState.lastFlushedToken();
+    this->reset();
 
     fFlushing = false;
-    this->reset();
 }
 
 void GrDrawTarget::reset() {
+    fLastPreparedBatch = 0;
     fBatches.reset();
 }
 
@@ -434,6 +441,11 @@ void GrDrawTarget::recordBatch(GrBatch* batch) {
         GrBATCH_INFO("\t\tFirstBatch\n");
     }
     fBatches.push_back().reset(SkRef(batch));
+    if (fBatches.count() > kMaxLookback) {
+        SkASSERT(fBatches.count() - kMaxLookback - fLastPreparedBatch == 1);
+        this->prepareN(1);
+        fLastPreparedBatch++;
+    }
 }
 
 ///////////////////////////////////////////////////////////////////////////////