From 5e6723203013b365c2a60158578f73abf480b8bf Mon Sep 17 00:00:00 2001
From: Jorge Canizales <jcanizales@google.com>
Date: Wed, 9 Mar 2016 13:34:28 -0800
Subject: [PATCH] Make Writeable with single handler robust against stream
Writers
---
src/objective-c/RxLibrary/GRXWriteable.m | 37 ++++++++++++++++++++----
1 file changed, 32 insertions(+), 5 deletions(-)
diff --git a/src/objective-c/RxLibrary/GRXWriteable.m b/src/objective-c/RxLibrary/GRXWriteable.m
index 2729d62b72..b122c04ce0 100644
--- a/src/objective-c/RxLibrary/GRXWriteable.m
+++ b/src/objective-c/RxLibrary/GRXWriteable.m
@@ -42,11 +42,38 @@
if (!handler) {
return [[self alloc] init];
}
- return [[self alloc] initWithValueHandler:^(id value) {
- handler(value, nil);
- } completionHandler:^(NSError *errorOrNil) {
- if (errorOrNil) {
- handler(nil, errorOrNil);
+ // We nilify this variable when the block is invoked, so that handler is only invoked once even if
+ // the writer tries to write multiple values.
+ __block GRXEventHandler eventHandler = ^(BOOL done, id value, NSError *error) {
+ // Nillify eventHandler before invoking handler, in case the latter causes the former to be
+ // executed recursively. Because blocks can be deallocated even during execution, we have to
+ // first retain handler locally to guarantee it's valid.
+ // TODO(jcanizales): Just turn this craziness into a simple subclass of GRXWriteable.
+ GRXSingleHandler singleHandler = handler;
+ eventHandler = nil;
+
+ if (value) {
+ singleHandler(value, nil);
+ } else if (error) {
+ singleHandler(nil, error);
+ } else {
+ NSDictionary *userInfo = @{
+ NSLocalizedDescriptionKey: @"The writer finished without producing any value."
+ };
+ // Even though RxLibrary is independent of gRPC, the domain and code here are, for the moment,
+ // set to the values of kGRPCErrorDomain and GRPCErrorCodeInternal. This way, the error formed
+ // is the one user of gRPC would expect if the server failed to produce a response.
+ //
+ // TODO(jcanizales): Figure out a way to keep errors of RxLibrary generic without making users
+ // of gRPC take care of two different error domains and error code enums. A possibility is to
+ // add error handling to GRXWriters or GRXWriteables, and use them to translate errors between
+ // the two domains.
+ singleHandler(nil, [NSError errorWithDomain:@"io.grpc" code:13 userInfo:userInfo]);
+ }
+ };
+ return [self writeableWithEventHandler:^(BOOL done, id value, NSError *error) {
+ if (eventHandler) {
+ eventHandler(done, value, error);
}
}];
}
--
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