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authorUlas Kozat <ulas.kozat@gmail.com>2016-05-15 21:31:15 -0700
committerUlas Kozat <ulas.kozat@gmail.com>2016-05-15 21:43:21 -0700
commit7893dd02c15f2a727eb50887c9ddb829fc71f556 (patch)
tree54efcdadfda729ec4301537d264f6ea4298716e9 /lib/thrift/transport/TZlibTransport.py
parent06f85217ae3d5c9b429bad94827caed0641cd120 (diff)
Simple mapper/scheduler/partitioner functions implemented
Change-Id: I553b196943022451d8dc4984fe37b2b228c8f4cf Signed-off-by: Ulas C. Kozat <ulas.kozat@huawei.com>
Diffstat (limited to 'lib/thrift/transport/TZlibTransport.py')
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diff --git a/lib/thrift/transport/TZlibTransport.py b/lib/thrift/transport/TZlibTransport.py
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+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+"""TZlibTransport provides a compressed transport and transport factory
+class, using the python standard library zlib module to implement
+data compression.
+"""
+
+from __future__ import division
+import zlib
+from cStringIO import StringIO
+from TTransport import TTransportBase, CReadableTransport
+
+
+class TZlibTransportFactory(object):
+ """Factory transport that builds zlib compressed transports.
+
+ This factory caches the last single client/transport that it was passed
+ and returns the same TZlibTransport object that was created.
+
+ This caching means the TServer class will get the _same_ transport
+ object for both input and output transports from this factory.
+ (For non-threaded scenarios only, since the cache only holds one object)
+
+ The purpose of this caching is to allocate only one TZlibTransport where
+ only one is really needed (since it must have separate read/write buffers),
+ and makes the statistics from getCompSavings() and getCompRatio()
+ easier to understand.
+ """
+ # class scoped cache of last transport given and zlibtransport returned
+ _last_trans = None
+ _last_z = None
+
+ def getTransport(self, trans, compresslevel=9):
+ """Wrap a transport, trans, with the TZlibTransport
+ compressed transport class, returning a new
+ transport to the caller.
+
+ @param compresslevel: The zlib compression level, ranging
+ from 0 (no compression) to 9 (best compression). Defaults to 9.
+ @type compresslevel: int
+
+ This method returns a TZlibTransport which wraps the
+ passed C{trans} TTransport derived instance.
+ """
+ if trans == self._last_trans:
+ return self._last_z
+ ztrans = TZlibTransport(trans, compresslevel)
+ self._last_trans = trans
+ self._last_z = ztrans
+ return ztrans
+
+
+class TZlibTransport(TTransportBase, CReadableTransport):
+ """Class that wraps a transport with zlib, compressing writes
+ and decompresses reads, using the python standard
+ library zlib module.
+ """
+ # Read buffer size for the python fastbinary C extension,
+ # the TBinaryProtocolAccelerated class.
+ DEFAULT_BUFFSIZE = 4096
+
+ def __init__(self, trans, compresslevel=9):
+ """Create a new TZlibTransport, wrapping C{trans}, another
+ TTransport derived object.
+
+ @param trans: A thrift transport object, i.e. a TSocket() object.
+ @type trans: TTransport
+ @param compresslevel: The zlib compression level, ranging
+ from 0 (no compression) to 9 (best compression). Default is 9.
+ @type compresslevel: int
+ """
+ self.__trans = trans
+ self.compresslevel = compresslevel
+ self.__rbuf = StringIO()
+ self.__wbuf = StringIO()
+ self._init_zlib()
+ self._init_stats()
+
+ def _reinit_buffers(self):
+ """Internal method to initialize/reset the internal StringIO objects
+ for read and write buffers.
+ """
+ self.__rbuf = StringIO()
+ self.__wbuf = StringIO()
+
+ def _init_stats(self):
+ """Internal method to reset the internal statistics counters
+ for compression ratios and bandwidth savings.
+ """
+ self.bytes_in = 0
+ self.bytes_out = 0
+ self.bytes_in_comp = 0
+ self.bytes_out_comp = 0
+
+ def _init_zlib(self):
+ """Internal method for setting up the zlib compression and
+ decompression objects.
+ """
+ self._zcomp_read = zlib.decompressobj()
+ self._zcomp_write = zlib.compressobj(self.compresslevel)
+
+ def getCompRatio(self):
+ """Get the current measured compression ratios (in,out) from
+ this transport.
+
+ Returns a tuple of:
+ (inbound_compression_ratio, outbound_compression_ratio)
+
+ The compression ratios are computed as:
+ compressed / uncompressed
+
+ E.g., data that compresses by 10x will have a ratio of: 0.10
+ and data that compresses to half of ts original size will
+ have a ratio of 0.5
+
+ None is returned if no bytes have yet been processed in
+ a particular direction.
+ """
+ r_percent, w_percent = (None, None)
+ if self.bytes_in > 0:
+ r_percent = self.bytes_in_comp / self.bytes_in
+ if self.bytes_out > 0:
+ w_percent = self.bytes_out_comp / self.bytes_out
+ return (r_percent, w_percent)
+
+ def getCompSavings(self):
+ """Get the current count of saved bytes due to data
+ compression.
+
+ Returns a tuple of:
+ (inbound_saved_bytes, outbound_saved_bytes)
+
+ Note: if compression is actually expanding your
+ data (only likely with very tiny thrift objects), then
+ the values returned will be negative.
+ """
+ r_saved = self.bytes_in - self.bytes_in_comp
+ w_saved = self.bytes_out - self.bytes_out_comp
+ return (r_saved, w_saved)
+
+ def isOpen(self):
+ """Return the underlying transport's open status"""
+ return self.__trans.isOpen()
+
+ def open(self):
+ """Open the underlying transport"""
+ self._init_stats()
+ return self.__trans.open()
+
+ def listen(self):
+ """Invoke the underlying transport's listen() method"""
+ self.__trans.listen()
+
+ def accept(self):
+ """Accept connections on the underlying transport"""
+ return self.__trans.accept()
+
+ def close(self):
+ """Close the underlying transport,"""
+ self._reinit_buffers()
+ self._init_zlib()
+ return self.__trans.close()
+
+ def read(self, sz):
+ """Read up to sz bytes from the decompressed bytes buffer, and
+ read from the underlying transport if the decompression
+ buffer is empty.
+ """
+ ret = self.__rbuf.read(sz)
+ if len(ret) > 0:
+ return ret
+ # keep reading from transport until something comes back
+ while True:
+ if self.readComp(sz):
+ break
+ ret = self.__rbuf.read(sz)
+ return ret
+
+ def readComp(self, sz):
+ """Read compressed data from the underlying transport, then
+ decompress it and append it to the internal StringIO read buffer
+ """
+ zbuf = self.__trans.read(sz)
+ zbuf = self._zcomp_read.unconsumed_tail + zbuf
+ buf = self._zcomp_read.decompress(zbuf)
+ self.bytes_in += len(zbuf)
+ self.bytes_in_comp += len(buf)
+ old = self.__rbuf.read()
+ self.__rbuf = StringIO(old + buf)
+ if len(old) + len(buf) == 0:
+ return False
+ return True
+
+ def write(self, buf):
+ """Write some bytes, putting them into the internal write
+ buffer for eventual compression.
+ """
+ self.__wbuf.write(buf)
+
+ def flush(self):
+ """Flush any queued up data in the write buffer and ensure the
+ compression buffer is flushed out to the underlying transport
+ """
+ wout = self.__wbuf.getvalue()
+ if len(wout) > 0:
+ zbuf = self._zcomp_write.compress(wout)
+ self.bytes_out += len(wout)
+ self.bytes_out_comp += len(zbuf)
+ else:
+ zbuf = ''
+ ztail = self._zcomp_write.flush(zlib.Z_SYNC_FLUSH)
+ self.bytes_out_comp += len(ztail)
+ if (len(zbuf) + len(ztail)) > 0:
+ self.__wbuf = StringIO()
+ self.__trans.write(zbuf + ztail)
+ self.__trans.flush()
+
+ @property
+ def cstringio_buf(self):
+ """Implement the CReadableTransport interface"""
+ return self.__rbuf
+
+ def cstringio_refill(self, partialread, reqlen):
+ """Implement the CReadableTransport interface for refill"""
+ retstring = partialread
+ if reqlen < self.DEFAULT_BUFFSIZE:
+ retstring += self.read(self.DEFAULT_BUFFSIZE)
+ while len(retstring) < reqlen:
+ retstring += self.read(reqlen - len(retstring))
+ self.__rbuf = StringIO(retstring)
+ return self.__rbuf