GitHub user kdubb opened a pull request:
https://github.com/apache/thrift/pull/539
Thrift 2905 & - Modern Objective-C & Swift compatibility.
This pull request is really just to start a conversation about how to move
forward with the changes I've made to the Thrift Cocoa library and generator.
The nature of the changes are that they are big & a bit destructive.
Unfortunately there wasn't much getting around that. Hopefully working with
the community we can agree on the best way to integrate these changes. Maybe
just as another "language" binding instead of replacing the current "cocoa".
## Goals ##
* Modernize generated code
* Increase asynchronous support (both blocks and promises)
* Remove use of deprecated classes & paradigms (e.g NSException,
NSURLSession)
* Greater Swift interoperability
## Major Changes ##
* Use NSError based error & exception handling
* Optionally generate PromiseKit methods in the asynchronous clients
* Change asynchronous clients to be fully multi-thread safe
* Added THTTPSessionTransport, asynchronous HTTP transport that works with
NSURLSession
* Use NS_ENUM enumerations (with standard format)
* Struct fields & their "set" flags now use properties exclusively
* Removed instance variables from public headers
* Remove retain/release stubs
* Remove all deallocs
# Why? #
We made some very large changes. Here's why...
## NSException to NSError ##
The use of NSException has been very problematic for us. Aside from the
direction of Apple, which is to use exceptions for "fatal errors" only, it
comes with a host of issues. First, Clang still produces incorrect code in many
cases when using exceptions. Take this code for example...
```objective-c
executeBlockAndReturnValue(^{
@try {
return value;
}
@catch(NSException *e) {
}
// should be a return statement on this branch, Clang produces no
error/warning
});
```
Clang should produce an error but doesn't. This is only a nuisance though,
much worse are the ARC failures we've found when catching exceptions up the
stack. Secondly, Swift has no support for exceptions (and with Swift 2 we've
seen it won't ever use NSException).
It's for these reasons we changed the the Cocoa library to use NSError, all
of the generated (synchronous) methods now follow the Apple guidelines and
return a BOOL or object pointer with a last error parameter of type NSError**;
return values of NO or nil mean the error parameter is populated and the call
failed (or and exception was thrown from the server). These changes have been
made throughout the generated and library code.
*Synchronous Client Method Mapping*
Only synchronous method mappings are affected. The asynchronous methods
have ways to report errors out-of-band that don't require mapping types.
* Methods returning basic types are mapped to NSNumber/NSValue - nil
reports call failure/exception
* Methods returning VOID are mapped to return BOOL - NO reports call
failure/exception
* Methods returning Struct/String/Binary return the object value as normal
- nil reports call failure/exception
### NSError & Swift 2 ###
These changes conveniently take the form of Swift 2's error handling
system. This means that protocols and transports can be used from and written
in Swift and will be compatible with the current & future directions of Swift.
## ARC Only ##
ARC is here to stay; Apple deprecated everything else a few years ago. All
code related to maintaining backwards compatibly with non-ARC mode has been
removed.
## Mutl-Threaded Asynchronous Transports ##
The current implementations means that clients cannot be used in different
threads. This means the user is left to synchronize access to them or, as in
our case, build a client per thread to ensure parallelism.
Our changes have reengineered the way asynchronous works. Now,
asynchronous clients accept only protocol and async-transport factories. Each
call allocates a new transport and protocol binds them before use. This
provides the best options for parallelism with a fairly small overhead.
A note on performance... the alternative approaches, which we used in the
past, required thread local storage inside the transport which meant an
NSDictionary lookup (i.e. threadDictionary) for each read/write/flush. The new
approach only requires 2 simple object allocations. Much improved.
## NSURLSession (NSURLConnection is now deprecated) ##
The new THTTPSessionTransport replaces the old THTTPClient. It's both
asynchronous and uses the new NSURLSession classes for conformance in the new
iOS/OSX versions.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/reTXT/thrift THRIFT-2905
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/thrift/pull/539.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #539
----
commit a7e2544d55e366f1259afd508c3646cb64df716a
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T02:43:27Z
Modernized Cocoa
⢠Use NSError based error & exception handling
⢠Use NS_ENUM enumerations (with standard format)
⢠nullable & nonnull attributes for parameters
⢠Swift interoperability (nullability, enums & error handling)
⢠Removed instance variables from public header
⢠Remove retain/release stubs
⢠Remove all deallocs
commit e73f7b644cde831ed14729c0962a51d0476de788
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T18:32:19Z
Add optional support for PromiseKit to async clients
commit 1220b0a7d60d24680813dc214cd5464ebe0989b4
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T20:17:00Z
Fix analyzer surfaced issues with SSL socket
commit 0b91a7761c74e97783093885a92814f50aa03566
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T20:18:31Z
Protocols wrap transport errors with more information
The current message name & source file/line information is added to the
protocol error that wraps the transport error.
commit 9925c463fd40466a8f2974869af01048767938a8
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T22:58:47Z
Make async transports & clients mutl-thread safe
commit 467efe8878357c48f3b2080c82a28d0bf86c7bd8
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T23:32:34Z
Rename transport "Clients" to transports. Client is the terminology for the
top level object already.
commit fcc3ae3a47d0cbf4774b0ac8b7f543fe144db5cf
Author: Kevin Wooten <[email protected]>
Date: 2015-07-03T23:32:50Z
Fix async client init method
commit cb0f4325bef01ee9282a0055f5a29c415864fb9c
Author: Kevin Wooten <[email protected]>
Date: 2015-07-04T01:11:33Z
Fix setter name generation
commit 5ffe3478c01ee70e7489be196bc280aefe8ab5b0
Author: Kevin Wooten <[email protected]>
Date: 2015-07-04T01:11:55Z
Simplify NSError reading logic
commit 9a2bf0416d657ad643819aafa6943c1c8cc29ebc
Author: Kevin Wooten <[email protected]>
Date: 2015-07-04T01:12:51Z
Fix HTTP sessoin transport's response data loading
----
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