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Interfaces of Python GA API

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Nathaniel Manista 9 years ago
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      src/python/grpcio/grpc/__init__.py

758
src/python/grpcio/grpc/__init__.py
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""gRPC's Python API."""
__import__('pkg_resources').declare_namespace(__name__)
import abc
import enum
import six
from grpc._cython import cygrpc as _cygrpc
############################## Future Interface ###############################
class FutureTimeoutError(Exception):
"""Indicates that a method call on a Future timed out."""
class FutureCancelledError(Exception):
"""Indicates that the computation underlying a Future was cancelled."""
class Future(six.with_metaclass(abc.ABCMeta)):
"""A representation of a computation in another control flow.
Computations represented by a Future may be yet to be begun, may be ongoing,
or may have already completed.
"""
@abc.abstractmethod
def cancel(self):
"""Attempts to cancel the computation.
This method does not block.
Returns:
True if the computation has not yet begun, will not be allowed to take
place, and determination of both was possible without blocking. False
under all other circumstances including but not limited to the
computation's already having begun, the computation's already having
finished, and the computation's having been scheduled for execution on a
remote system for which a determination of whether or not it commenced
before being cancelled cannot be made without blocking.
"""
raise NotImplementedError()
@abc.abstractmethod
def cancelled(self):
"""Describes whether the computation was cancelled.
This method does not block.
Returns:
True if the computation was cancelled any time before its result became
immediately available. False under all other circumstances including but
not limited to this object's cancel method not having been called and
the computation's result having become immediately available.
"""
raise NotImplementedError()
@abc.abstractmethod
def running(self):
"""Describes whether the computation is taking place.
This method does not block.
Returns:
True if the computation is scheduled to take place in the future or is
taking place now, or False if the computation took place in the past or
was cancelled.
"""
raise NotImplementedError()
@abc.abstractmethod
def done(self):
"""Describes whether the computation has taken place.
This method does not block.
Returns:
True if the computation is known to have either completed or have been
unscheduled or interrupted. False if the computation may possibly be
executing or scheduled to execute later.
"""
raise NotImplementedError()
@abc.abstractmethod
def result(self, timeout=None):
"""Accesses the outcome of the computation or raises its exception.
This method may return immediately or may block.
Args:
timeout: The length of time in seconds to wait for the computation to
finish or be cancelled, or None if this method should block until the
computation has finished or is cancelled no matter how long that takes.
Returns:
The return value of the computation.
Raises:
FutureTimeoutError: If a timeout value is passed and the computation does
not terminate within the allotted time.
FutureCancelledError: If the computation was cancelled.
Exception: If the computation raised an exception, this call will raise
the same exception.
"""
raise NotImplementedError()
@abc.abstractmethod
def exception(self, timeout=None):
"""Return the exception raised by the computation.
This method may return immediately or may block.
Args:
timeout: The length of time in seconds to wait for the computation to
terminate or be cancelled, or None if this method should block until
the computation is terminated or is cancelled no matter how long that
takes.
Returns:
The exception raised by the computation, or None if the computation did
not raise an exception.
Raises:
FutureTimeoutError: If a timeout value is passed and the computation does
not terminate within the allotted time.
FutureCancelledError: If the computation was cancelled.
"""
raise NotImplementedError()
@abc.abstractmethod
def traceback(self, timeout=None):
"""Access the traceback of the exception raised by the computation.
This method may return immediately or may block.
Args:
timeout: The length of time in seconds to wait for the computation to
terminate or be cancelled, or None if this method should block until
the computation is terminated or is cancelled no matter how long that
takes.
Returns:
The traceback of the exception raised by the computation, or None if the
computation did not raise an exception.
Raises:
FutureTimeoutError: If a timeout value is passed and the computation does
not terminate within the allotted time.
FutureCancelledError: If the computation was cancelled.
"""
raise NotImplementedError()
@abc.abstractmethod
def add_done_callback(self, fn):
"""Adds a function to be called at completion of the computation.
The callback will be passed this Future object describing the outcome of
the computation.
If the computation has already completed, the callback will be called
immediately.
Args:
fn: A callable taking this Future object as its single parameter.
"""
raise NotImplementedError()
################################ gRPC Enums ##################################
@enum.unique
class ChannelConnectivity(enum.Enum):
"""Mirrors grpc_connectivity_state in the gRPC Core.
Attributes:
IDLE: The channel is idle.
CONNECTING: The channel is connecting.
READY: The channel is ready to conduct RPCs.
TRANSIENT_FAILURE: The channel has seen a failure from which it expects to
recover.
FATAL_FAILURE: The channel has seen a failure from which it cannot recover.
"""
IDLE = (_cygrpc.ConnectivityState.idle, 'idle')
CONNECTING = (_cygrpc.ConnectivityState.connecting, 'connecting')
READY = (_cygrpc.ConnectivityState.ready, 'ready')
TRANSIENT_FAILURE = (
_cygrpc.ConnectivityState.transient_failure, 'transient failure')
FATAL_FAILURE = (_cygrpc.ConnectivityState.fatal_failure, 'fatal failure')
@enum.unique
class StatusCode(enum.Enum):
"""Mirrors grpc_status_code in the gRPC Core."""
OK = (_cygrpc.StatusCode.ok, 'ok')
CANCELLED = (_cygrpc.StatusCode.cancelled, 'cancelled')
UNKNOWN = (_cygrpc.StatusCode.unknown, 'unknown')
INVALID_ARGUMENT = (
_cygrpc.StatusCode.invalid_argument, 'invalid argument')
DEADLINE_EXCEEDED = (
_cygrpc.StatusCode.deadline_exceeded, 'deadline exceeded')
NOT_FOUND = (_cygrpc.StatusCode.not_found, 'not found')
ALREADY_EXISTS = (_cygrpc.StatusCode.already_exists, 'already exists')
PERMISSION_DENIED = (
_cygrpc.StatusCode.permission_denied, 'permission denied')
RESOURCE_EXHAUSTED = (
_cygrpc.StatusCode.resource_exhausted, 'resource exhausted')
FAILED_PRECONDITION = (
_cygrpc.StatusCode.failed_precondition, 'failed precondition')
ABORTED = (_cygrpc.StatusCode.aborted, 'aborted')
OUT_OF_RANGE = (_cygrpc.StatusCode.out_of_range, 'out of range')
UNIMPLEMENTED = (_cygrpc.StatusCode.unimplemented, 'unimplemented')
INTERNAL = (_cygrpc.StatusCode.internal, 'internal')
UNAVAILABLE = (_cygrpc.StatusCode.unavailable, 'unavailable')
DATA_LOSS = (_cygrpc.StatusCode.data_loss, 'data loss')
UNAUTHENTICATED = (_cygrpc.StatusCode.unauthenticated, 'unauthenticated')
############################# gRPC Exceptions ################################
class RpcError(Exception):
"""Raised by the gRPC library to indicate non-OK-status RPC termination."""
############################## Shared Context ################################
class RpcContext(six.with_metaclass(abc.ABCMeta)):
"""Provides RPC-related information and action."""
@abc.abstractmethod
def is_active(self):
"""Describes whether the RPC is active or has terminated."""
raise NotImplementedError()
@abc.abstractmethod
def time_remaining(self):
"""Describes the length of allowed time remaining for the RPC.
Returns:
A nonnegative float indicating the length of allowed time in seconds
remaining for the RPC to complete before it is considered to have timed
out, or None if no deadline was specified for the RPC.
"""
raise NotImplementedError()
@abc.abstractmethod
def cancel(self):
"""Cancels the RPC.
Idempotent and has no effect if the RPC has already terminated.
"""
raise NotImplementedError()
@abc.abstractmethod
def add_callback(self, callback):
"""Registers a callback to be called on RPC termination.
Args:
callback: A no-parameter callable to be called on RPC termination.
Returns:
True if the callback was added and will be called later; False if the
callback was not added and will not later be called (because the RPC
already terminated or some other reason).
"""
raise NotImplementedError()
######################### Invocation-Side Context ############################
class Call(six.with_metaclass(abc.ABCMeta, RpcContext)):
"""Invocation-side utility object for an RPC."""
@abc.abstractmethod
def initial_metadata(self):
"""Accesses the initial metadata from the service-side of the RPC.
This method blocks until the value is available.
Returns:
The initial metadata as a sequence of pairs of bytes.
"""
raise NotImplementedError()
@abc.abstractmethod
def trailing_metadata(self):
"""Accesses the trailing metadata from the service-side of the RPC.
This method blocks until the value is available.
Returns:
The trailing metadata as a sequence of pairs of bytes.
"""
raise NotImplementedError()
@abc.abstractmethod
def code(self):
"""Accesses the status code emitted by the service-side of the RPC.
This method blocks until the value is available.
Returns:
The StatusCode value for the RPC.
"""
raise NotImplementedError()
@abc.abstractmethod
def details(self):
"""Accesses the details value emitted by the service-side of the RPC.
This method blocks until the value is available.
Returns:
The bytes of the details of the RPC.
"""
raise NotImplementedError()
######################## Multi-Callable Interfaces ###########################
class UnaryUnaryMultiCallable(six.with_metaclass(abc.ABCMeta)):
"""Affords invoking a unary-unary RPC."""
@abc.abstractmethod
def __call__(self, request, timeout=None, metadata=None, with_call=False):
"""Synchronously invokes the underlying RPC.
Args:
request: The request value for the RPC.
timeout: An optional duration of time in seconds to allow for the RPC.
metadata: An optional sequence of pairs of bytes to be transmitted to the
service-side of the RPC.
with_call: Whether or not to include return a Call for the RPC in addition
to the response.
Returns:
The response value for the RPC, and a Call for the RPC if with_call was
set to True at invocation.
Raises:
RpcError: Indicating that the RPC terminated with non-OK status. The
raised RpcError will also be a Call for the RPC affording the RPC's
metadata, status code, and details.
"""
raise NotImplementedError()
@abc.abstractmethod
def future(self, request, timeout=None, metadata=None):
"""Asynchronously invokes the underlying RPC.
Args:
request: The request value for the RPC.
timeout: An optional duration of time in seconds to allow for the RPC.
metadata: An optional sequence of pairs of bytes to be transmitted to the
service-side of the RPC.
Returns:
An object that is both a Call for the RPC and a Future. In the event of
RPC completion, the return Future's result value will be the response
message of the RPC. Should the event terminate with non-OK status, the
returned Future's exception value will be an RpcError.
"""
raise NotImplementedError()
class UnaryStreamMultiCallable(six.with_metaclass(abc.ABCMeta)):
"""Affords invoking a unary-stream RPC."""
@abc.abstractmethod
def __call__(self, request, timeout=None, metadata=None):
"""Invokes the underlying RPC.
Args:
request: The request value for the RPC.
timeout: An optional duration of time in seconds to allow for the RPC.
metadata: An optional sequence of pairs of bytes to be transmitted to the
service-side of the RPC.
Returns:
An object that is both a Call for the RPC and an iterator of response
values. Drawing response values from the returned iterator may raise
RpcError indicating termination of the RPC with non-OK status.
"""
raise NotImplementedError()
class StreamUnaryMultiCallable(six.with_metaclass(abc.ABCMeta)):
"""Affords invoking a stream-unary RPC in any call style."""
@abc.abstractmethod
def __call__(
self, request_iterator, timeout=None, metadata=None, with_call=False):
"""Synchronously invokes the underlying RPC.
Args:
request_iterator: An iterator that yields request values for the RPC.
timeout: An optional duration of time in seconds to allow for the RPC.
metadata: An optional sequence of pairs of bytes to be transmitted to the
service-side of the RPC.
with_call: Whether or not to include return a Call for the RPC in addition
to the response.
Returns:
The response value for the RPC, and a Call for the RPC if with_call was
set to True at invocation.
Raises:
RpcError: Indicating that the RPC terminated with non-OK status. The
raised RpcError will also be a Call for the RPC affording the RPC's
metadata, status code, and details.
"""
raise NotImplementedError()
@abc.abstractmethod
def future(self, request_iterator, timeout=None, metadata=None):
"""Asynchronously invokes the underlying RPC.
Args:
request_iterator: An iterator that yields request values for the RPC.
timeout: An optional duration of time in seconds to allow for the RPC.
metadata: An optional sequence of pairs of bytes to be transmitted to the
service-side of the RPC.
Returns:
An object that is both a Call for the RPC and a Future. In the event of
RPC completion, the return Future's result value will be the response
message of the RPC. Should the event terminate with non-OK status, the
returned Future's exception value will be an RpcError.
"""
raise NotImplementedError()
class StreamStreamMultiCallable(six.with_metaclass(abc.ABCMeta)):
"""Affords invoking a stream-stream RPC in any call style."""
@abc.abstractmethod
def __call__(self, request_iterator, timeout=None, metadata=None):
"""Invokes the underlying RPC.
Args:
request_iterator: An iterator that yields request values for the RPC.
timeout: An optional duration of time in seconds to allow for the RPC.
metadata: An optional sequence of pairs of bytes to be transmitted to the
service-side of the RPC.
Returns:
An object that is both a Call for the RPC and an iterator of response
values. Drawing response values from the returned iterator may raise
RpcError indicating termination of the RPC with non-OK status.
"""
raise NotImplementedError()
############################# Channel Interface ##############################
class Channel(six.with_metaclass(abc.ABCMeta)):
"""Affords RPC invocation via generic methods."""
@abc.abstractmethod
def subscribe(self, callback, try_to_connect=False):
"""Subscribes to this Channel's connectivity.
Args:
callback: A callable to be invoked and passed a ChannelConnectivity value
describing this Channel's connectivity. The callable will be invoked
immediately upon subscription and again for every change to this
Channel's connectivity thereafter until it is unsubscribed or this
Channel object goes out of scope.
try_to_connect: A boolean indicating whether or not this Channel should
attempt to connect if it is not already connected and ready to conduct
RPCs.
"""
raise NotImplementedError()
@abc.abstractmethod
def unsubscribe(self, callback):
"""Unsubscribes a callback from this Channel's connectivity.
Args:
callback: A callable previously registered with this Channel from having
been passed to its "subscribe" method.
"""
raise NotImplementedError()
@abc.abstractmethod
def unary_unary(
self, method, request_serializer=None, response_deserializer=None):
"""Creates a UnaryUnaryMultiCallable for a unary-unary method.
Args:
method: The name of the RPC method.
Returns:
A UnaryUnaryMultiCallable value for the named unary-unary method.
"""
raise NotImplementedError()
@abc.abstractmethod
def unary_stream(
self, method, request_serializer=None, response_deserializer=None):
"""Creates a UnaryStreamMultiCallable for a unary-stream method.
Args:
method: The name of the RPC method.
Returns:
A UnaryStreamMultiCallable value for the name unary-stream method.
"""
raise NotImplementedError()
@abc.abstractmethod
def stream_unary(
self, method, request_serializer=None, response_deserializer=None):
"""Creates a StreamUnaryMultiCallable for a stream-unary method.
Args:
method: The name of the RPC method.
Returns:
A StreamUnaryMultiCallable value for the named stream-unary method.
"""
raise NotImplementedError()
@abc.abstractmethod
def stream_stream(
self, method, request_serializer=None, response_deserializer=None):
"""Creates a StreamStreamMultiCallable for a stream-stream method.
Args:
method: The name of the RPC method.
Returns:
A StreamStreamMultiCallable value for the named stream-stream method.
"""
raise NotImplementedError()
########################## Service-Side Context ##############################
class ServicerContext(six.with_metaclass(abc.ABCMeta, RpcContext)):
"""A context object passed to method implementations."""
@abc.abstractmethod
def invocation_metadata(self):
"""Accesses the metadata from the invocation-side of the RPC.
Returns:
The invocation metadata object as a sequence of pairs of bytes.
"""
raise NotImplementedError()
@abc.abstractmethod
def peer(self):
"""Identifies the peer that invoked the RPC being serviced.
Returns:
A string identifying the peer that invoked the RPC being serviced.
"""
raise NotImplementedError()
@abc.abstractmethod
def send_initial_metadata(self, initial_metadata):
"""Sends the initial metadata value to the invocation-side of the RPC.
This method need not be called by method implementations if they have no
service-side initial metadata to transmit.
Args:
initial_metadata: The initial metadata of the RPC as a sequence of pairs
of bytes.
"""
raise NotImplementedError()
@abc.abstractmethod
def set_trailing_metadata(self, trailing_metadata):
"""Accepts the trailing metadata value of the RPC.
This method need not be called by method implementations if they have no
service-side trailing metadata to transmit.
Args:
trailing_metadata: The trailing metadata of the RPC as a sequence of pairs
of bytes.
"""
raise NotImplementedError()
@abc.abstractmethod
def set_code(self, code):
"""Accepts the status code of the RPC.
This method need not be called by method implementations if they wish the
gRPC runtime to determine the status code of the RPC.
Args:
code: The integer status code of the RPC to be transmitted to the
invocation side of the RPC.
"""
raise NotImplementedError()
@abc.abstractmethod
def set_details(self, details):
"""Accepts the service-side details of the RPC.
This method need not be called by method implementations if they have no
details to transmit.
Args:
details: The details bytes of the RPC to be transmitted to
the invocation side of the RPC.
"""
raise NotImplementedError()
##################### Service-Side Handler Interfaces ########################
class RpcMethodHandler(six.with_metaclass(abc.ABCMeta)):
"""An implementation of a single RPC method.
Attributes:
request_streaming: Whether the RPC supports exactly one request message or
any arbitrary number of request messages.
response_streaming: Whether the RPC supports exactly one response message or
any arbitrary number of response messages.
request_deserializer: A callable behavior that accepts a byte string and
returns an object suitable to be passed to this object's business logic,
or None to indicate that this object's business logic should be passed the
raw request bytes.
response_serializer: A callable behavior that accepts an object produced by
this object's business logic and returns a byte string, or None to
indicate that the byte strings produced by this object's business logic
should be transmitted on the wire as they are.
unary_unary: This object's application-specific business logic as a callable
value that takes a request value and a ServicerContext object and returns
a response value. Only non-None if both request_streaming and
response_streaming are False.
unary_stream: This object's application-specific business logic as a
callable value that takes a request value and a ServicerContext object and
returns an iterator of response values. Only non-None if request_streaming
is False and response_streaming is True.
stream_unary: This object's application-specific business logic as a
callable value that takes an iterator of request values and a
ServicerContext object and returns a response value. Only non-None if
request_streaming is True and response_streaming is False.
stream_stream: This object's application-specific business logic as a
callable value that takes an iterator of request values and a
ServicerContext object and returns an iterator of response values. Only
non-None if request_streaming and response_streaming are both True.
"""
class HandlerCallDetails(six.with_metaclass(abc.ABCMeta)):
"""Describes an RPC that has just arrived for service.
Attributes:
method: The method name of the RPC.
invocation_metadata: The metadata from the invocation side of the RPC.
"""
class GenericRpcHandler(six.with_metaclass(abc.ABCMeta)):
"""An implementation of arbitrarily many RPC methods."""
@abc.abstractmethod
def service(self, handler_call_details):
"""Services an RPC (or not).
Args:
handler_call_details: A HandlerCallDetails describing the RPC.
Returns:
An RpcMethodHandler with which the RPC may be serviced, or None to
indicate that this object will not be servicing the RPC.
"""
raise NotImplementedError()
############################# Server Interface ###############################
class Server(six.with_metaclass(abc.ABCMeta)):
"""Services RPCs."""
@abc.abstractmethod
def add_generic_rpc_handlers(self, generic_rpc_handlers):
"""Registers GenericRpcHandlers with this Server.
This method is only safe to call before the server is started.
Args:
generic_rpc_handlers: An iterable of GenericRpcHandlers that will be used
to service RPCs after this Server is started.
"""
raise NotImplementedError()
@abc.abstractmethod
def add_insecure_port(self, address):
"""Reserves a port for insecure RPC service once this Server becomes active.
This method may only be called before calling this Server's start method is
called.
Args:
address: The address for which to open a port.
Returns:
An integer port on which RPCs will be serviced after this link has been
started. This is typically the same number as the port number contained
in the passed address, but will likely be different if the port number
contained in the passed address was zero.
"""
raise NotImplementedError()
@abc.abstractmethod
def start(self):
"""Starts this Server's service of RPCs.
This method may only be called while the server is not serving RPCs (i.e. it
is not idempotent).
"""
raise NotImplementedError()
@abc.abstractmethod
def stop(self, grace):
"""Stops this Server's service of RPCs.
All calls to this method immediately stop service of new RPCs. When existing
RPCs are aborted is controlled by the grace period parameter passed to this
method.
This method may be called at any time and is idempotent. Passing a smaller
grace value than has been passed in a previous call will have the effect of
stopping the Server sooner. Passing a larger grace value than has been
passed in a previous call will not have the effect of stopping the server
later.
Args:
grace: A duration of time in seconds to allow existing RPCs to complete
before being aborted by this Server's stopping. If None, this method
will block until the server is completely stopped.
Returns:
A threading.Event that will be set when this Server has completely
stopped. The returned event may not be set until after the full grace
period (if some ongoing RPC continues for the full length of the period)
of it may be set much sooner (such as if this Server had no RPCs underway
at the time it was stopped or if all RPCs that it had underway completed
very early in the grace period).
"""
raise NotImplementedError()

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