Couple tweaks to generate less garbage #451
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lutovich
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Added static final instances of `CompletableFuture` completed with `null` and `false`. This is done to reduce object allocation.
`HashMap` has default load factor of 0.75. It is often not enough to specify desired initial capacity in order for the map to not resize. This commit adds a helper method to create `HashMap` that will not resize.
Because it is faster to check port integers and only then check host strings.
`CompletionStage` that holds current connection can't be failed because all exceptions are handled when writing to the field. This commit removes unneeded method that tried to handle all exceptions.
It previously needed to store channels for purging of network connections on error. Now this functionality is not needed because driver never performs an active purge. This commit makes `ActiveChannelTracker` only store number of active connections per host, not the actual connections.
Summary is created when driver receives SUCCESS or FAILURE for PULL_ALL message. It previously had it's own special handling of SUCCESS and FAILURE in the response handler. This commit simplifies it by making summary piggyback on FAILURE.
This test is often the first one to download and install shared neo4j database. It might take more than 20 seconds to do this on a slow connection. Thus timeout is increased to 60 seconds.
Method `InternalStatementResultCursor#listAsync()` returns a future containing list of all records. Records can potentially be transformed using the `#listAsync(Function<Record, T>)` overload. Implementation used to be built on top of `#nextAsync()` and invoked it recursively in `ForkJoinPool.commonPool` workers. This resulted in quite a lot of garbage generation because every record needed to be wrapped in a `CompletableFuture`. Also execution in the separate threads resulted in increased CPU load. `PullAllResponseHandler` is responsible for buffering of incoming records in a queue. This commit makes `#listAsync()` implementation wait for final PULL_ALL message and then transform the queue into list. When FAILURE is received for PULL_ALL resulting future is failed. When SUCCESS is received for PULL_ALL given transformation function is applied to the queue of records and resulting list is returned. This results in less garbage being generated because no intermediate `CompletableFuture`s are created.
lutovich
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ali-ince
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Dec 20, 2017
| @@ -276,7 +277,7 @@ public TypeSystem typeSystem() | |||
| { | |||
| if ( connectionStage == null ) | |||
| { | |||
| return completedFuture( false ); | |||
| return completedWithFalse(); | |||
There was a problem hiding this comment.
Since connectionStage is initialized with completedWithNull, this connectionStage == null check can be removed or checked against completedWithNull.
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PR makes the following changes:
CompletableFutures completed withnullandfalseHashMaps so that they do not resizeBoltServerAddress#equals()now checks port first and then hostActiveChannelTrackeronly stores channel counts, not actual channels#listAsync()to transform records buffered in the queue