adding rate limiting and retry logic

BackupPC_archiveHost_s3

@@ -12,7 +12,9 @@
 # sharedkey = 'amazon aws shared key'
 # gpgsymmetrickey = 'gpg symmetric key -- make it good, but do not lose it'
 
+import base64
 import glob
+import md5
 import os
 import secrets
 import sys
@@ -35,6 +37,103 @@ loghandler.setFormatter(logformatter)
 logger.addHandler(loghandler)
 logger.setLevel(logging.DEBUG)
 
+# classes
+class MyKey(Key):
+    def _compute_md5(self, fp):
+        """
+        @type fp: file
+        @param fp: File pointer to the file to MD5 hash
+        
+        @rtype: string
+        @return: MD5 Hash of the file in fp
+        """
+        m = md5.new()
+        s = fp.fastread(self.BufferSize)
+        while s:
+            m.update(s)
+            s = fp.fastread(self.BufferSize)
+        self.md5 = m.hexdigest()
+        self.base64md5 = base64.encodestring(m.digest())
+        if self.base64md5[-1] == '\n':
+            self.base64md5 = self.base64md5[0:-1]
+        self.size = fp.tell()
+        fp.seek(0)
+
+class SlowFile:
+    def __init__(self, name, mode='rb', speed=19200):
+        """Open a rate-limited filehandle.  Supports read for now.
+        name, mode as normal; speed in bytes per second"""
+
+        self.name = name
+        self.mode = mode
+        self.speed = speed
+
+        self.fd = open(self.name, self.mode)
+
+        self.closed = False
+        self.encoding = None
+
+        self.delayfactor = 1
+        self.lastblocktargettime = None
+
+        self.lastdebug = 0
+
+    def close(self):
+        self.closed = True
+        return self.fd.close()
+
+    def fastread(self, len=1024):
+        return self.fd.read(len)
+
+    def flush(self):
+        return self.fd.flush()
+
+    def fileno(self):
+        return self.fd.fileno()
+
+    def isatty(self):
+        return self.fd.isatty()
+
+    def tell(self):
+        return self.fd.tell()
+
+    def read(self, len=1024):
+        if not self.fd:
+            raise IOError
+
+        starttime = time.time()
+
+        if starttime < self.lastblocktargettime:
+            # we're early
+            sleepfor = self.lastblocktargettime - starttime
+            time.sleep(sleepfor)
+            if self.delayfactor > 1:
+                self.delayfactor -= 0.02
+        else:
+            # we're late; something got slow.
+            self.delayfactor += 0.01
+
+        if self.delayfactor < 1:
+            self.delayfactor = 1
+        if self.delayfactor > 5:
+            self.delayfactor = 5
+
+        targetspeed = self.speed/float(self.delayfactor)
+        self.lastblocktargettime = time.time() + len/float(targetspeed)
+
+        if time.time() > self.lastdebug+60:
+            logger.debug('Target %i bytes/second (%i kilobits/second), delay factor %.2f, block len %i' % (targetspeed, targetspeed*8/1024, self.delayfactor, len))
+            self.lastdebug = time.time()
+
+        return self.fd.read(len)
+
+    def seek(self, offset, mode=0):
+        self.delayfactor = 1
+        return self.fd.seek(offset, mode)
+
+    def write(self, data):
+        raise NotImplementedError
+
 # functions
 def is_exe(fpath):
     return os.path.exists(fpath) and os.access(fpath, os.X_OK)
@@ -89,11 +188,13 @@ def handle_progress(transmitted, pending):
 def send_file(bucket, filename):
     if bucket.get_key(filename):
         logging.error('Duplicate filename %s! I hope that is OK.' % filename)
-    k = Key(bucket)
+    k = MyKey(bucket)
     k.key = os.path.basename(filename)
     logging.info('Uploading %s...' % os.path.basename(filename))
 
-    k.set_contents_from_filename(filename, cb=handle_progress)
+    fd = SlowFile(name=filename, mode='rb')
+
+    k.set_contents_from_file(fd, cb=handle_progress)
 
     return k
  
@@ -154,7 +255,7 @@ if returncode != 0:
     logger.error('%s died with exit code %i' % (cmd, returncode))
     sys.exit(1)
 
-logging.info('Beginning post-processing of %s #%i' % (host, bkupNum))
+logging.info('Beginning post-processing of %i files from %s #%i' % (len(glob.glob(fileglob)), host, bkupNum))
 
 for i in sorted(glob.glob(fileglob)):
     if secrets.gpgsymmetrickey:
@@ -162,11 +263,22 @@ for i in sorted(glob.glob(fileglob)):
     else:
         sendfile = i
 
-    key = send_file(bucket, sendfile)
-    key.set_metadata('backuppc_cmd', cmd)
-    key.set_metadata('backuppc_mesg', mesg)
-    key.set_acl('private')
-    key.close()
+    retry_count = 0
+    max_retries = 10
+
+    while retry_count <= max_retries:
+        try:
+            key = send_file(bucket, sendfile)
+            key.set_metadata('backuppc_cmd', cmd)
+            key.set_metadata('backuppc_mesg', mesg)
+            key.set_acl('private')
+            key.close()
+            retry_count = max_retries+1
+        except boto.exception.S3ResponseError as e:
+            retry_count += 1
+            sleeptime = 2**retry_count
+            log.error('Encountered S3 exception %s, retrying in %i seconds (%i/%i)' % (e, sleeptime, retry_count, max_retries))
+            time.sleep(sleeptime)
 
     os.unlink(sendfile)