Updates

ETB-API/venv/lib/python3.12/site-packages/prometheus_client/mmap_dict.py

@@ -0,0 +1,145 @@
+import json
+import mmap
+import os
+import struct
+from typing import List
+
+_INITIAL_MMAP_SIZE = 1 << 16
+_pack_integer_func = struct.Struct(b'i').pack
+_pack_two_doubles_func = struct.Struct(b'dd').pack
+_unpack_integer = struct.Struct(b'i').unpack_from
+_unpack_two_doubles = struct.Struct(b'dd').unpack_from
+
+
+# struct.pack_into has atomicity issues because it will temporarily write 0 into
+# the mmap, resulting in false reads to 0 when experiencing a lot of writes.
+# Using direct assignment solves this issue.
+
+
+def _pack_two_doubles(data, pos, value, timestamp):
+    data[pos:pos + 16] = _pack_two_doubles_func(value, timestamp)
+
+
+def _pack_integer(data, pos, value):
+    data[pos:pos + 4] = _pack_integer_func(value)
+
+
+def _read_all_values(data, used=0):
+    """Yield (key, value, timestamp, pos). No locking is performed."""
+
+    if used <= 0:
+        # If not valid `used` value is passed in, read it from the file.
+        used = _unpack_integer(data, 0)[0]
+
+    pos = 8
+
+    while pos < used:
+        encoded_len = _unpack_integer(data, pos)[0]
+        # check we are not reading beyond bounds
+        if encoded_len + pos > used:
+            raise RuntimeError('Read beyond file size detected, file is corrupted.')
+        pos += 4
+        encoded_key = data[pos:pos + encoded_len]
+        padded_len = encoded_len + (8 - (encoded_len + 4) % 8)
+        pos += padded_len
+        value, timestamp = _unpack_two_doubles(data, pos)
+        yield encoded_key.decode('utf-8'), value, timestamp, pos
+        pos += 16
+
+
+class MmapedDict:
+    """A dict of doubles, backed by an mmapped file.
+
+    The file starts with a 4 byte int, indicating how much of it is used.
+    Then 4 bytes of padding.
+    There's then a number of entries, consisting of a 4 byte int which is the
+    size of the next field, a utf-8 encoded string key, padding to a 8 byte
+    alignment, and then a 8 byte float which is the value and a 8 byte float
+    which is a UNIX timestamp in seconds.
+
+    Not thread safe.
+    """
+
+    def __init__(self, filename, read_mode=False):
+        self._f = open(filename, 'rb' if read_mode else 'a+b')
+        self._fname = filename
+        capacity = os.fstat(self._f.fileno()).st_size
+        if capacity == 0:
+            self._f.truncate(_INITIAL_MMAP_SIZE)
+            capacity = _INITIAL_MMAP_SIZE
+        self._capacity = capacity
+        self._m = mmap.mmap(self._f.fileno(), self._capacity,
+                            access=mmap.ACCESS_READ if read_mode else mmap.ACCESS_WRITE)
+
+        self._positions = {}
+        self._used = _unpack_integer(self._m, 0)[0]
+        if self._used == 0:
+            self._used = 8
+            _pack_integer(self._m, 0, self._used)
+        else:
+            if not read_mode:
+                for key, _, _, pos in self._read_all_values():
+                    self._positions[key] = pos
+
+    @staticmethod
+    def read_all_values_from_file(filename):
+        with open(filename, 'rb') as infp:
+            # Read the first block of data, including the first 4 bytes which tell us
+            # how much of the file (which is preallocated to _INITIAL_MMAP_SIZE bytes) is occupied.
+            data = infp.read(mmap.PAGESIZE)
+            used = _unpack_integer(data, 0)[0]
+            if used > len(data):  # Then read in the rest, if needed.
+                data += infp.read(used - len(data))
+        return _read_all_values(data, used)
+
+    def _init_value(self, key):
+        """Initialize a value. Lock must be held by caller."""
+        encoded = key.encode('utf-8')
+        # Pad to be 8-byte aligned.
+        padded = encoded + (b' ' * (8 - (len(encoded) + 4) % 8))
+        value = struct.pack(f'i{len(padded)}sdd'.encode(), len(encoded), padded, 0.0, 0.0)
+        while self._used + len(value) > self._capacity:
+            self._capacity *= 2
+            self._f.truncate(self._capacity)
+            self._m = mmap.mmap(self._f.fileno(), self._capacity)
+        self._m[self._used:self._used + len(value)] = value
+
+        # Update how much space we've used.
+        self._used += len(value)
+        _pack_integer(self._m, 0, self._used)
+        self._positions[key] = self._used - 16
+
+    def _read_all_values(self):
+        """Yield (key, value, pos). No locking is performed."""
+        return _read_all_values(data=self._m, used=self._used)
+
+    def read_all_values(self):
+        """Yield (key, value, timestamp). No locking is performed."""
+        for k, v, ts, _ in self._read_all_values():
+            yield k, v, ts
+
+    def read_value(self, key):
+        if key not in self._positions:
+            self._init_value(key)
+        pos = self._positions[key]
+        return _unpack_two_doubles(self._m, pos)
+
+    def write_value(self, key, value, timestamp):
+        if key not in self._positions:
+            self._init_value(key)
+        pos = self._positions[key]
+        _pack_two_doubles(self._m, pos, value, timestamp)
+
+    def close(self):
+        if self._f:
+            self._m.close()
+            self._m = None
+            self._f.close()
+            self._f = None
+
+
+def mmap_key(metric_name: str, name: str, labelnames: List[str], labelvalues: List[str], help_text: str) -> str:
+    """Format a key for use in the mmap file."""
+    # ensure labels are in consistent order for identity
+    labels = dict(zip(labelnames, labelvalues))
+    return json.dumps([metric_name, name, labels, help_text], sort_keys=True)