feat: small speed up to writing outgoing packets (#1316)

src/zeroconf/_protocol/outgoing.pxd

@@ -32,6 +32,7 @@ cdef object LOGGING_DEBUG
 
 cdef cython.tuple BYTE_TABLE
 cdef cython.tuple SHORT_LOOKUP
+cdef cython.dict LONG_LOOKUP
 
 cdef class DNSOutgoing:
 
@@ -70,7 +71,7 @@ cdef class DNSOutgoing:
         index=cython.uint,
         length=cython.uint
     )
-    cdef cython.bint _write_record(self, DNSRecord record, object now)
+    cdef cython.bint _write_record(self, DNSRecord record, float now)
 
     @cython.locals(class_=cython.uint)
     cdef _write_record_class(self, DNSEntry record)
@@ -91,7 +92,7 @@ cdef class DNSOutgoing:
 
     cdef bint _has_more_to_add(self, unsigned int questions_offset, unsigned int answer_offset, unsigned int authority_offset, unsigned int additional_offset)
 
-    cdef _write_ttl(self, DNSRecord record, object now)
+    cdef _write_ttl(self, DNSRecord record, float now)
 
     @cython.locals(
         labels=cython.list,

src/zeroconf/_protocol/outgoing.py

@@ -31,6 +31,8 @@
 from .._logger import log
 from ..const import (
     _CLASS_UNIQUE,
+    _DNS_HOST_TTL,
+    _DNS_OTHER_TTL,
     _DNS_PACKET_HEADER_LEN,
     _FLAGS_QR_MASK,
     _FLAGS_QR_QUERY,
@@ -57,6 +59,7 @@
 
 BYTE_TABLE = tuple(PACK_BYTE(i) for i in range(256))
 SHORT_LOOKUP = tuple(PACK_SHORT(i) for i in range(SHORT_CACHE_MAX))
+LONG_LOOKUP = {i: PACK_LONG(i) for i in (_DNS_OTHER_TTL, _DNS_HOST_TTL, 0)}
 
 
 class State(enum.Enum):
@@ -242,7 +245,12 @@ def write_short(self, value: int_) -> None:
 
     def _write_int(self, value: Union[float, int]) -> None:
         """Writes an unsigned integer to the packet"""
-        self.data.append(PACK_LONG(int(value)))
+        value_as_int = int(value)
+        long_bytes = LONG_LOOKUP.get(value_as_int)
+        if long_bytes is not None:
+            self.data.append(long_bytes)
+        else:
+            self.data.append(PACK_LONG(value_as_int))
         self.size += 4
 
     def write_string(self, value: bytes_) -> None: