started repackaging
This commit is contained in:
Sandy Walsh
parent
0c898146a0
commit
be6dee825c
231
var_strings.py
231
var_strings.py
@ -3,18 +3,6 @@ import datetime
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import json
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import struct
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event = {"event_type": "nova.compute.run_instance.start",
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"generated": datetime.datetime.utcnow(),
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"request_id": "req-1234abcd5678efgh",
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"source": "n-compute-1973",
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"payload": {
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"foo": 123,
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"blah": "abc",
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"zoo": False
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}
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}
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def handle_datetime(obj):
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if isinstance(obj, datetime.datetime):
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if obj.utcoffset() is not None:
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@ -26,86 +14,161 @@ def handle_datetime(obj):
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return millis
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def InvalidVersion(Exception):
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pass
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def OutOfSync(Exception):
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pass
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BOR_MAGIC_NUMBER = 0x69867884
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class Version1(object):
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# Version 1 SCHEMA
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# ----------------
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# i = 0x69867884 (EVNT)
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# h = version
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# i = metadata block length
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# i = raw notification block length
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# i = 0x00000000 EOR
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# Metadata dict block
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# i = number of strings (N) - key/value = 2 strings
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# N * i = length of key followed by length of value
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# N * (*s) = key followed by value
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# Raw notification block
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# i = length of raw data block
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# *s = raw data
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# EXAMPLE
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#--------
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# With above Event and Metadata
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#
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# Header schema: "ihiii"
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# Metadata length: 119
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# Raw notification length: 201
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# Metadata = 6 strings (3 key-value pairs)
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# Metadata schema: "iiiiiii6s14s10s31s10s20s"
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# ------ key/value
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# ------ key/value
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# ----- key/value
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# ------ length of the 6 strings
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# - 12 entries (6 string sizes + 6 strings)
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# Raw notification: "i197s"
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# ---- json notification
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# - 197
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def __init__(self):
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self.header_schema = "ihiii"
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self.header_size = struct.calcsize(self.header_schema)
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def pack(self, notification, metadata):
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nsize = len(notification)
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raw_block_schema = "i%ds" % nsize
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raw_block = struct.pack(raw_block_schema, nsize, notification)
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metadata_items = ["i"] # appended with N "%ds"'s
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metadata_values = [len(metadata) * 4] # [n]=key, [n+1]=value
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for key, value in metadata.iteritems():
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metadata_items.append("i")
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metadata_items.append("i")
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metadata_values.append(len(key))
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metadata_values.append(len(value))
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for key, value in metadata.iteritems():
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metadata_items.append("%ds" % len(key))
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metadata_values.append(key)
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metadata_items.append("%ds" % len(value))
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metadata_values.append(value)
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metadata_schema = "".join(metadata_items)
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metadata = struct.pack(metadata_schema, *metadata_values)
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header = struct.pack(self.header_schema, BOR_MAGIC_NUMBER, 1,
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struct.calcsize(metadata_schema),
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struct.calcsize(raw_block_schema), 0)
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return (header, metadata, raw_block)
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def unpack(self, file_handle):
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header_bytes = file_handle.read(self.header_size)
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header = struct.unpack(self.header_schema, header_bytes)
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if header[0] != BOR_MAGIC_NUMBER:
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raise OutOfSync()
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if header[1] != 1:
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raise InvalidVersion("Expected V1, got V%d" % header[1])
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metadata_bytes = file_handle.read(header[2])
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num_strings = struct.unpack_from("i", metadata_bytes)
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offset = struct.calcsize("i")
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lengths = num_strings[0] / 2
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lengths_schema = "i" * lengths
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key_value_sizes = struct.unpack_from(lengths_schema, metadata_bytes,
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offset=offset)
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key_value_schema_list = ["%ds" % sz for sz in key_value_sizes]
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key_value_schema = "".join(key_value_schema_list)
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offset += struct.calcsize(lengths_schema)
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key_values = struct.unpack_from(key_value_schema, metadata_bytes,
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offset=offset)
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metadata = dict((key_values[n], key_values[n+1])
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for n in range(len(key_values))[::2])
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raw = file_handle.read(header[3])
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raw_len = struct.unpack_from("i", raw)
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offset = struct.calcsize("i")
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raw_json = struct.unpack_from("%ds" % raw_len[0], raw, offset=offset)
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notification = json.loads(raw_json[0])
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return (metadata, notification)
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VERSIONS = {1: Version1()}
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CURRENT_VERSION = 1
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def get_version_handler(version=CURRENT_VERSION):
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global VERSIONS
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version_handler = VERSIONS.get(version)
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if not version_handler:
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raise InvalidVersion()
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return version_handler
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def pack_notification(notification, metadata, version=CURRENT_VERSION):
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version_handler = get_version_handler(version)
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return version_handler.pack(notification, metadata)
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def unpack_notification(file_handle, version=CURRENT_VERSION):
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version_handler = get_version_handler(version)
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return version_handler.unpack(file_handle)
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event = {"event_type": "nova.compute.run_instance.start",
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"generated": datetime.datetime.utcnow(),
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"request_id": "req-1234abcd5678efgh",
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"source": "n-compute-1973",
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"payload": {
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"foo": 123,
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"blah": "abc",
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"zoo": False
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}
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}
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json_event = json.dumps(event, default=handle_datetime)
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metadata = {'request_id': event['request_id'],
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'event_type': event['event_type'],
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'source': event['source'],
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}
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CURRENT_VERSION = 1
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# Version 1 SCHEMA
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# ----------------
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# i = 0x69867884 (EVNT)
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# h = version
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# i = metadata block length
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# i = raw notification block length
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# i = 0x00000000 EOR
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# Metadata block
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# i = number of strings
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# [i, i] = length of key, length of value
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# [*s, *s] = key, value
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# Raw notification block
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# *s = raw data
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raw_block_schema = "%ds" % len(json_event)
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raw_block = struct.pack(raw_block_schema, json_event)
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metadata_items = ["i"] # appended with N "%ds"'s
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metadata_values = [len(metadata) * 4] # [n]=key, [n+1]=value
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for key, value in metadata.iteritems():
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metadata_items.append("i")
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metadata_items.append("i")
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metadata_values.append(len(key))
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metadata_values.append(len(value))
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for key, value in metadata.iteritems():
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metadata_items.append("%ds" % len(key))
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metadata_values.append(key)
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metadata_items.append("%ds" % len(value))
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metadata_values.append(value)
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metadata_schema = "".join(metadata_items)
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metadata = struct.pack(metadata_schema, *metadata_values)
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header_schema = "ihiii"
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header_size = struct.calcsize(header_schema)
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header = struct.pack(header_schema, 0x69867884, CURRENT_VERSION,
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struct.calcsize(metadata_schema),
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struct.calcsize(raw_block_schema), 0)
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binary = pack_notification(json_event, metadata)
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with open("test.dat", "wb") as f:
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f.write(header)
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f.write(metadata)
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f.write(raw_block)
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for block in binary:
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f.write(block)
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with open("test.dat", "rb") as f:
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header = f.read(header_size)
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header = struct.unpack(header_schema, header)
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print "Marker:", hex(header[0])
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print "Version:", header[1]
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print "Metadata length:", header[2]
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print "Raw notification:", header[3]
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print "EOR:", header[4]
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metadata = f.read(header[2])
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num_strings = struct.unpack_from("i", metadata)
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print "Num metadata strings:", num_strings
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offset = struct.calcsize("i")
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lengths = num_strings[0] / 2
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lengths_schema = "i" * lengths
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print "Lengths schema:", lengths_schema
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key_value_sizes = struct.unpack_from(lengths_schema, metadata,
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offset=offset)
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key_value_schema_list = ["%ds" % sz for sz in key_value_sizes]
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key_value_schema = "".join(key_value_schema_list)
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offset += struct.calcsize(lengths_schema)
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key_values = struct.unpack_from(key_value_schema, metadata,
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offset=offset)
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metadata_dict = dict((key_values[n], key_values[n+1])
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for n in range(len(key_values))[::2])
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print "Key Value schema:", key_value_schema
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print "Metadata:", metadata_dict
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metadata, notification = unpack_notification(f)
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print "Metadata:", metadata
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print "Notification:", notification
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