add file streaming support

stream.py

@@ -0,0 +1,33 @@
+import time
+import common
+import wave
+
+
+class FileBuffer(object):
+
+    SAMPLES = 4096
+    BUFSIZE = int(SAMPLES * wave.bytes_per_sample)
+    WAIT = 0.1
+    TIMEOUT = 2.0
+
+    def __init__(self, fd):
+        self.fd = fd
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        block = bytearray()
+        finish_time = time.time() + self.TIMEOUT
+        while time.time() <= finish_time:
+            left = self.BUFSIZE - len(block)
+            data = self.fd.read(left)
+            if data:
+                block.extend(data)
+            if len(block) == self.BUFSIZE:
+                _, values = common.loads(str(block))
+                return values
+
+            time.sleep(self.WAIT)
+
+        raise IOError('timeout')

test_stream.py

@@ -0,0 +1,22 @@
+import stream
+import wave
+
+
+def test():
+    p = wave.record('-', stdout=wave.sp.PIPE)
+    f = stream.FileBuffer(p.stdout)
+
+    result = zip(range(10), f)
+    p.stop()
+
+    j = 0
+    for i, buf in result:
+        assert i == j
+        assert len(buf) == f.SAMPLES
+        j += 1
+
+    try:
+        for buf in f:
+            pass
+    except IOError as e:
+        assert str(e) == 'timeout'