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resolve PromiseClient requests in order

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Vaci Koblizek 2020-11-12 20:12:10 +00:00
parent cd8e096f3f
commit d526eca4b9
1 changed files with 16 additions and 37 deletions
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53
runtime-rpc/src/main/java/org/capnproto/RpcState.java
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@ -1500,63 +1500,42 @@ final class RpcState<VatId> {
private class RpcPipeline implements PipelineHook { private class RpcPipeline implements PipelineHook {
private final Question question; private final Question question;
private PipelineState state = PipelineState.WAITING;
private RpcResponse resolved;
private Throwable broken;
final HashMap<List<PipelineOp>, ClientHook> clientMap = new HashMap<>(); final HashMap<List<PipelineOp>, ClientHook> clientMap = new HashMap<>();
final CompletableFuture<RpcResponse> redirectLater; final CompletableFuture<RpcResponse> redirectLater;
final CompletableFuture<java.lang.Void> resolveSelf;
RpcPipeline(Question question, RpcPipeline(Question question,
CompletableFuture<RpcResponse> redirectLater) { CompletableFuture<RpcResponse> redirectLater) {
this.question = question; this.question = question;
this.redirectLater = redirectLater; this.redirectLater = redirectLater;
this.resolveSelf = this.redirectLater
.thenAccept(response -> {
this.state = PipelineState.RESOLVED;
this.resolved = response;
})
.exceptionally(exc -> {
this.state = PipelineState.BROKEN;
this.broken = exc;
return null;
});
} }
RpcPipeline(Question question) { RpcPipeline(Question question) {
this(question, null);
// never resolves // never resolves
this.question = question;
this.redirectLater = null;
this.resolveSelf = null;
} }
@Override @Override
public ClientHook getPipelinedCap(PipelineOp[] ops) { public ClientHook getPipelinedCap(PipelineOp[] ops) {
// We differ from the C++ implementation here.
// Previously, we would just store and return the resolved client, but this
// could cause tail calls to execute out of order.
// So instead we always chain resolution on the redirectLater promise, which
// ensures that each call initiated from this PromiseClient is executed in order.
// TODO avoid conversion to/from ArrayList? // TODO avoid conversion to/from ArrayList?
var key = new ArrayList<>(Arrays.asList(ops)); var key = new ArrayList<>(Arrays.asList(ops));
var hook = this.clientMap.computeIfAbsent(key, k -> { return this.clientMap.computeIfAbsent(key, k -> {
switch (state) { var pipelineClient = new PipelineClient(this.question, ops);
case WAITING: { if (this.redirectLater == null) {
var pipelineClient = new PipelineClient(this.question, ops); // This pipeline will never get redirected, so just return the PipelineClient.
if (this.redirectLater == null) { return pipelineClient;
// This pipeline will never get redirected, so just return the PipelineClient.
return pipelineClient;
}
var resolutionPromise = this.redirectLater.thenApply(
response -> response.getResults().getPipelinedCap(ops));
return new PromiseClient(pipelineClient, resolutionPromise, null);
}
case RESOLVED:
return resolved.getResults().getPipelinedCap(ops);
default:
return Capability.newBrokenCap(broken);
} }
var resolutionPromise = this.redirectLater.thenApply(
response -> response.getResults().getPipelinedCap(ops));
return new PromiseClient(pipelineClient, resolutionPromise, null);
}); });
return hook;
} }
} }