comparison mercurial/wireproto.py @ 25912:cbbdd085c991

batching: migrate basic noop batching into peer.peer

"Real" batching only makes sense for wirepeers, but it greatly
simplifies the clients of peer instances if they can be ignorant to
actual batching capabilities of that peer. By moving the
not-really-batched batching code into peer.peer, all peer instances
now work with the batching API, thus simplifying users.

This leaves a couple of name forwards in wirepeer.py. Originally I had
planned to clean those up, but it kind of unclarifies other bits of
code that want to use batching, so I think it makes sense for the
names to stay exposed by wireproto. Specifically, almost nothing is
currently aware of peer (see largefiles.proto for an example), so
making them be aware of the peer module *and* the wireproto module
seems like some abstraction leakage. I *think* the right long-term fix
would actually be to make wireproto an implementation detail that
clients wouldn't need to know about, but I don't really know what that
would entail at the moment.

As far as I'm aware, no clients of batching in third-party extensions
will need updating, which is nice icing.

25910:b4a85ddadcb9

        """return 4096 chunks from a changegroup object

        Some protocols may have compressed the contents."""
        raise NotImplementedError()

# abstract batching support

class future(object):
    '''placeholder for a value to be set later'''
    def set(self, value):
        if util.safehasattr(self, 'value'):
            raise error.RepoError("future is already set")
        self.value = value

class batcher(object):
    '''base class for batches of commands submittable in a single request

    All methods invoked on instances of this class are simply queued and
    return a a future for the result. Once you call submit(), all the queued
    calls are performed and the results set in their respective futures.
    '''
    def __init__(self):
        self.calls = []
    def __getattr__(self, name):
        def call(*args, **opts):
            resref = future()
            self.calls.append((name, args, opts, resref,))
            return resref
        return call
    def submit(self):
        pass

class localbatch(batcher):
    '''performs the queued calls directly'''
    def __init__(self, local):
        batcher.__init__(self)
        self.local = local
    def submit(self):
        for name, args, opts, resref in self.calls:
            resref.set(getattr(self.local, name)(*args, **opts))

class remotebatch(batcher):
    '''batches the queued calls; uses as few roundtrips as possible'''
    def __init__(self, remote):
        '''remote must support _submitbatch(encbatch) and
        _submitone(op, encargs)'''
        batcher.__init__(self)
        self.remote = remote
    def submit(self):
        req, rsp = [], []
        for name, args, opts, resref in self.calls:
            mtd = getattr(self.remote, name)

        for encres, r in zip(encresults, rsp):
            batchable, encresref, resref = r
            encresref.set(encres)
            resref.set(batchable.next())

def batchable(f):
    '''annotation for batchable methods

    Such methods must implement a coroutine as follows:

    @batchable
    def sample(self, one, two=None):
        # Handle locally computable results first:
        if not one:
            yield "a local result", None
        # Build list of encoded arguments suitable for your wire protocol:
        encargs = [('one', encode(one),), ('two', encode(two),)]
        # Create future for injection of encoded result:
        encresref = future()
        # Return encoded arguments and future:
        yield encargs, encresref
        # Assuming the future to be filled with the result from the batched
        # request now. Decode it:
        yield decode(encresref.value)

    The decorator returns a function which wraps this coroutine as a plain
    method, but adds the original method as an attribute called "batchable",
    which is used by remotebatch to split the call into separate encoding and
    decoding phases.
    '''
    def plain(*args, **opts):
        batchable = f(*args, **opts)
        encargsorres, encresref = batchable.next()
        if not encresref:
            return encargsorres # a local result in this case
        self = args[0]
        encresref.set(self._submitone(f.func_name, encargsorres))
        return batchable.next()
    setattr(plain, 'batchable', f)
    return plain

# list of nodes encoding / decoding

def decodelist(l, sep=' '):
    if l:

25912:cbbdd085c991

        """return 4096 chunks from a changegroup object

        Some protocols may have compressed the contents."""
        raise NotImplementedError()

class remotebatch(peer.batcher):
    '''batches the queued calls; uses as few roundtrips as possible'''
    def __init__(self, remote):
        '''remote must support _submitbatch(encbatch) and
        _submitone(op, encargs)'''
        peer.batcher.__init__(self)
        self.remote = remote
    def submit(self):
        req, rsp = [], []
        for name, args, opts, resref in self.calls:
            mtd = getattr(self.remote, name)

        for encres, r in zip(encresults, rsp):
            batchable, encresref, resref = r
            encresref.set(encres)
            resref.set(batchable.next())

# Forward a couple of names from peer to make wireproto interactions
# slightly more sensible.
batchable = peer.batchable
future = peer.future

# list of nodes encoding / decoding

def decodelist(l, sep=' '):
    if l: