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Removing unnecessary use of Math.ceil in HTTP/2 priority algorithm.

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Motivation:

We're currently using Math.ceil which isn't necessary. We should exchange for a lighter weight operation.

Modifications:

Changing the logic to just ensure that we allocate at least one byte to the child rather than always performing a ceil.

Result:

Slight performance improvement in the priority algorithm.
This commit is contained in:
nmittler 2015-03-30 11:34:57 -07:00
parent 9737cc6cc9
commit ba9f214303
1 changed files with 8 additions and 3 deletions
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11
codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2RemoteFlowController.java
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@ -235,8 +235,10 @@ public class DefaultHttp2RemoteFlowController implements Http2RemoteFlowControll
}
/**
* This will allocate bytes by stream weight and priority for the entire tree rooted at {@code parent}, but does
* not write any bytes.
* This will allocate bytes by stream weight and priority for the entire tree rooted at {@code parent}, but does not
* write any bytes. The connection window is generally distributed amongst siblings according to their weight,
* however we need to ensure that the entire connection window is used (assuming streams have >= connection window
* bytes to send) and we may need some sort of rounding to accomplish this.
*
* @param parent The parent of the tree.
* @param connectionWindow The connection window this is available for use at this point in the tree.
@ -282,7 +284,10 @@ public class DefaultHttp2RemoteFlowController implements Http2RemoteFlowControll
int weight = child.weight();
double weightRatio = weight / (double) totalWeight;
int bytesForTree = Math.min(nextConnectionWindow, (int) Math.ceil(connectionWindow * weightRatio));
// In order to make progress toward the connection window due to possible rounding errors, we make sure
// that each stream (with data to send) is given at least 1 byte toward the connection window.
int connectionWindowChunk = Math.max(1, (int) (connectionWindow * weightRatio));
int bytesForTree = Math.min(nextConnectionWindow, connectionWindowChunk);
int bytesForChild = Math.min(state.streamableBytes(), bytesForTree);
if (bytesForChild > 0) {