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App Engine Python SDK
v1.6.9 rev.445
The Python runtime is available as an experimental Preview feature.
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Public Member Functions | |
def | __init__ |
def | flush |
def | register_pool |
def | get_pool |
Public Attributes | |
mapreduce_spec | |
task_retry_count | |
mapreduce_id | |
shard_id | |
counters | |
MapReduce execution context. The main purpose of Context is to facilitate IO. User code, input reader, and output writer code can plug in pools (see Pool class) to Context to batch operations. There is a single Context instance associated with each worker thread. It can be accessed via context.get(). handlers.MapperWorkerHandler creates this instance before any IO code (input_reader, output_writer, user functions) is called. Each Pool decides how to batch and when to flush. Context and all its pools are flushed by the end of a slice. Upon error in slice execution, what is flushed is undefined. (See _Counters for an exception). Properties: mapreduce_spec: current mapreduce specification as model.MapreduceSpec.
def google.appengine.ext.mapreduce.context.Context.__init__ | ( | self, | |
mapreduce_spec, | |||
shard_state, | |||
task_retry_count = 0 |
|||
) |
Constructor. Args: mapreduce_spec: mapreduce specification as model.MapreduceSpec. shard_state: an instance of model.ShardState. This has to be the same instance as the one MapperWorkerHandler mutates. All mutations are flushed to datastore in the end of the slice. task_retry_count: how many times this task has been retried.
def google.appengine.ext.mapreduce.context.Context.flush | ( | self | ) |
Flush all information recorded in context.
def google.appengine.ext.mapreduce.context.Context.get_pool | ( | self, | |
key | |||
) |
Obtains an instance of registered pool. Args: key: pool key as string. Returns: an instance of the pool registered earlier, or None.
def google.appengine.ext.mapreduce.context.Context.register_pool | ( | self, | |
key, | |||
pool | |||
) |
Register an arbitrary pool to be flushed together with this context. Args: key: pool key as string. pool: a pool instance.