Introduce SharedTemporaryFile (bis)

fipy/tools/__init__.py

@@ -45,6 +45,7 @@
 from .dimensions.physicalField import PhysicalField
 from fipy.tools.numerix import *
 from fipy.tools.vitals import Vitals
+from fipy.tools.sharedtempfile import SharedTemporaryFile
 
 __all__ = ["serialComm",
            "parallelComm",
@@ -54,7 +55,8 @@
            "PhysicalField",
            "Vitals",
            "serial",
-           "parallel"]
+           "parallel",
+           "SharedTemporaryFile"]
 from future.utils import text_to_native_str
 __all__ = [text_to_native_str(n) for n in __all__]
 

fipy/tools/sharedtempfile.py

@@ -0,0 +1,195 @@
+"""This module provides a generic, high-level interface for
+creating shared temporary files.  All of the interfaces
+provided by this module can be used without fear of race conditions.
+"""
+
+from tempfile import NamedTemporaryFile, template, _TemporaryFileWrapper
+from future import utils
+
+from fipy.tools import parallelComm
+
+__all__ = ["SharedTemporaryFile"]
+
+# Silence linting errors that come from following conventions of
+# tempfile package.
+# pylint: disable=invalid-name
+# pylint: disable=redefined-builtin
+# pylint: disable=too-many-arguments
+
+if utils.PY3:
+    import io as _io
+
+    def SharedTemporaryFile(
+        mode="w+b",
+        buffering=-1,
+        encoding=None,
+        newline=None,
+        suffix="",
+        prefix=template,
+        dir=None,
+        delete=True,
+        communicator=parallelComm,
+    ):
+        """Create a temporary file shared by all MPI ranks.
+
+        The file is created as `NamedTemporaryFile` would do it.
+        The name of the returned file-like object is accessible as its
+        ``name`` attribute.  The file will be automatically deleted when it
+        is closed unless the `delete` argument is set to False.
+
+        >>> from fipy.tools import SharedTemporaryFile, parallelComm
+        >>> with SharedTemporaryFile(mode='w+', suffix=".tmp") as tmpFile:
+        ...     # write on processor 0
+        ...     if parallelComm.procID == 0:
+        ...         _ = tmpFile.write("shared text")
+        ...
+        ...     parallelComm.Barrier()
+        ...
+        ...     # read on all processors
+        ...     _ = tmpFile.seek(0)
+        ...     txt = tmpFile.read()
+        >>> print(txt)
+        shared text
+
+        Parameters
+        ----------
+        prefix, suffix, dir : str
+            As for mkstemp
+        mode : str
+            The mode argument to io.open (default "w+b")
+        buffering : int
+            The buffer size argument to io.open (default -1)
+        encoding : str or None
+            The encoding argument to io.open (default None)
+        newline : str or None
+            The newline argument to io.open (default None)
+        delete : bool
+            Whether the file is deleted on close (default True)
+        communicator : ~fipy.tools.comms.commWrapper.CommWrapper
+            MPI communicator describing ranks to share with.  A duck-typed
+            object with `procID` and `Nproc` attributes is sufficient.
+
+        Returns
+        -------
+        file-like object
+
+        See Also
+        --------
+        tempfile.NamedTemporaryFile, tempfile.mkstemp, io.open
+
+        """
+
+        if communicator.procID == 0:
+            file = NamedTemporaryFile(
+                mode=mode,
+                buffering=buffering,
+                encoding=encoding,
+                newline=newline,
+                suffix=suffix,
+                prefix=prefix,
+                dir=dir,
+                delete=delete,
+            )
+            fname = file.name
+        else:
+            fname = None
+
+        fname = communicator.bcast(fname)
+
+        if communicator.procID != 0:
+            file = _io.open(
+                fname, mode, buffering=buffering, newline=newline, encoding=encoding
+            )
+            # let procID 0 handle delete
+            file = _TemporaryFileWrapper(file, fname, delete=False)
+
+        return file
+
+
+else:
+
+    def SharedTemporaryFile(
+        mode="w+b",
+        bufsize=-1,
+        suffix="",
+        prefix=template,
+        dir=None,
+        delete=True,
+        communicator=parallelComm,
+    ):
+        """Create a temporary file shared by all MPI ranks.
+
+        The file is created as `NamedTemporaryFile` would do it.
+        The name of the returned file-like object is accessible as its
+        ``name`` attribute.  The file will be automatically deleted when it
+        is closed unless the `delete` argument is set to False.
+
+        >>> from fipy.tools import SharedTemporaryFile, parallelComm
+        >>> with SharedTemporaryFile(mode='w+', suffix=".tmp") as tmpFile:
+        ...     # write on processor 0
+        ...     if parallelComm.procID == 0:
+        ...         _ = tmpFile.write("shared text")
+        ...
+        ...     parallelComm.Barrier()
+        ...
+        ...     # read on all processors
+        ...     _ = tmpFile.seek(0)
+        ...     txt = tmpFile.read()
+        >>> print(txt)
+        shared text
+
+        Parameters
+        ----------
+        prefix, suffix, dir : str
+            As for mkstemp
+        mode : str
+            The mode argument to os.fdopen (default "w+b")
+        bufsize : int
+            The buffer size argument to os.fdopen (default -1)
+        delete : bool
+            Whether the file is deleted on close (default True)
+        communicator : ~fipy.tools.comms.commWrapper.CommWrapper
+            MPI communicator describing ranks to share with.  A duck-typed
+            object with `procID` and `Nproc` attributes is sufficient
+
+        Returns
+        -------
+        file-like object
+
+        See Also
+        --------
+        tempfile.NamedTemporaryFile, tempfile.mkstemp, os.fdopen
+
+        """
+
+        if communicator.procID == 0:
+            file = NamedTemporaryFile(
+                mode=mode,
+                bufsize=bufsize,
+                suffix=suffix,
+                prefix=prefix,
+                dir=dir,
+                delete=delete,
+            )
+            fname = file.name
+        else:
+            fname = None
+
+        fname = communicator.bcast(fname)
+
+        if communicator.procID != 0:
+            file = open(fname, mode, bufsize)
+            # let procID 0 handle delete
+            file = _TemporaryFileWrapper(file, fname, delete=False)
+
+        return file
+
+
+def _test():
+    import fipy.tests.doctestPlus
+
+    return fipy.tests.doctestPlus.testmod()
+
+
+if __name__ == "__main__":
+    _test()

fipy/tools/test.py

@@ -10,6 +10,7 @@ def _suite():
             'numerix',
             'dump',
             'vector',
+            'sharedtempfile'
         ), base = __name__)
 
     return theSuite