pyhaystack.util package¶
Submodules¶
pyhaystack.util.asyncexc module¶
Asynchronous Exception Handler. This implements a small lightweight object for capturing an exception in a manner that can be passed in callback arguments then re-raised elsewhere for handling in the callback function.
Typical usage:
def _some_async_function(…, callback_fn):
try:
do some async op that may fail
result = ...
except: # Capture all exceptions
result = AsynchronousException()
callback_fn(result)
pyhaystack.util.filterbuilder module¶
Filter abstract syntax tree builder. These classes and functions attempt to build a filter string for use with ‘read’ operations by combining Python’s operators to trick it into producing the desired values.
Yes, we’re hijacking operators to do what they weren’t expected to do.
Typical usage:
from pyhaystack.util import filterbuilder as fb
# Get all historical points:
session.find_points(fb.Field('his'))
# All historical points in Brisbane timezone.
session.find_points(fb.Field('his') & ( fb.Field('tz') == fb.Scalar('Brisbane') ))
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class
pyhaystack.util.filterbuilder.And(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= 'and'¶
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class
pyhaystack.util.filterbuilder.Binary(x, y)¶
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class
pyhaystack.util.filterbuilder.Equal(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= '=='¶
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class
pyhaystack.util.filterbuilder.Field(value)¶
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class
pyhaystack.util.filterbuilder.GreaterThan(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= '>'¶
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class
pyhaystack.util.filterbuilder.GreaterThanOrEqual(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= '>='¶
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class
pyhaystack.util.filterbuilder.LessThan(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= '<'¶
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class
pyhaystack.util.filterbuilder.LessThanOrEqual(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= '<='¶
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class
pyhaystack.util.filterbuilder.Not(value)¶ Bases:
pyhaystack.util.filterbuilder.Unary-
OP= 'not'¶
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class
pyhaystack.util.filterbuilder.NotEqual(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= '!='¶
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class
pyhaystack.util.filterbuilder.Or(x, y)¶ Bases:
pyhaystack.util.filterbuilder.Binary-
OP= 'or'¶
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class
pyhaystack.util.filterbuilder.Scalar(value)¶
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class
pyhaystack.util.filterbuilder.Unary(value)¶
pyhaystack.util.state module¶
State machine interface. This is a base class for implementing state machines.
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class
pyhaystack.util.state.HaystackOperation(result_copy=True, result_deepcopy=True)¶ Bases:
objectA core state machine object. This implements the basic interface presented for all operations in pyhaystack.
Initialisation. This should be overridden by subclasses to accept and validate the inputs presented for the operation, raising an appropriate Exception subclass if the inputs are found to be invalid.
These should be stored here by the initialisation function as private variables in suitably sanitised form. The core state machine object shall then be created and stored before the object is returned to the caller.
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go()¶ Start processing the operation. This is called by the caller (so after all __init__ functions have executed) in order to begin the asynchronous operation.
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is_done¶ Return true if the operation is complete.
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is_failed¶ Return true if the result is an Exception.
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result¶ Return the result of the operation or raise its exception. Raises NotReadyError if not ready.
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state¶ Return the current state machine’s state.
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wait(timeout=None)¶ Wait for an operation to finish. This should NOT be called in the same thread as the thread executing the operation as this will deadlock.
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exception
pyhaystack.util.state.NotReadyError¶ Bases:
exceptions.ExceptionException raised when an attempt is made to retrieve the result of an operation before it is ready.
pyhaystack.util.tools module¶
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pyhaystack.util.tools.isBool(value)¶ Helper function to detect if a value is boolean
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pyhaystack.util.tools.isfloat(value)¶ Helper function to detect if a value is a float
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pyhaystack.util.tools.prettyprint(jsonData)¶ Pretty print json object