diff server/utils.py @ 328:46070aaf29ea

A bit of work on the server python
author Matt Johnston <matt@ucc.asn.au>
date Sat, 26 May 2012 10:17:27 +0800
parents
children b5925cb4f264
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/server/utils.py	Sat May 26 10:17:27 2012 +0800
@@ -0,0 +1,75 @@
+import os
+import sys
+import ctypes
+import time
+import select
+
+DEFAULT_TRIES = 3
+
+__all__ = ('monotonic_time', 'retry')
+
+clock_gettime = None
+no_clock_gettime = False
+def monotonic_time():
+    global clock_gettime
+    global no_clock_gettime
+    if no_clock_gettime:
+        return time.time()
+
+    class timespec(ctypes.Structure):
+        _fields_ = [
+            ('tv_sec', ctypes.c_long),
+            ('tv_nsec', ctypes.c_long)
+        ]
+    if not clock_gettime:
+        try:
+            librt = ctypes.CDLL('librt.so.0', use_errno=True)
+            clock_gettime = librt.clock_gettime
+            clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]
+        except:
+            print>>sys.stderr, "No clock_gettime(), using fake fallback."
+            no_clock_gettime = True
+            return time.time()
+        
+    t = timespec()
+    CLOCK_MONOTONIC = 1 # see <linux/time.h>
+
+    if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(t)) != 0:
+        errno_ = ctypes.get_errno()
+        raise OSError(errno_, os.strerror(errno_))
+    return t.tv_sec + t.tv_nsec * 1e-9
+
+# decorator, tries a number of times, returns None on failure, sleeps between
+# Must be used as "@retry()" if arguments are defaulted
+def retry(retries=DEFAULT_TRIES, try_time = 1):
+    def inner(func):
+        print "inner"
+        def new_f(*args, **kwargs):
+            print "newf"
+            for i in range(retries):
+                print "retry %d" % i
+                d = func(*args, **kwargs)
+                if d:
+                    return d
+                time.sleep(try_time)
+        new_f.func_name = func.func_name
+        return new_f
+    return inner
+
+def readline(sock):
+    timeout = READLINE_SELECT_TIMEOUT
+    buf = ''
+    while true:
+        (rlist, wlist, xlist) = select.select([sock], [], [], timeout)
+        if sock not in rlist:
+            # hit timeout
+            return None
+
+        c = sock.recv(1)
+        if c == '\r':
+            continue
+
+        buf.append(c)
+        if c == '\n':
+            return buf
+