Commit e91a5b12 authored by serge-sans-paille's avatar serge-sans-paille
Browse files

Bug 1884327 - faster perfect hash r=ahochheiden 

While we're at it, also remove the `six` layer, which slightly impacts
some callers.

Depends on D204009

Differential Revision: https://phabricator.services.mozilla.com/D204010
parent 66a10622

xpcom/components/gen_static_components.py

+8 −4
Original line number Diff line number Diff line
@@ -920,14 +920,18 @@ def gen_substs(manifests): 


    cid_phf = PerfectHash(modules, PHF_SIZE, key=lambda module: module.cid.bytes)



    contract_phf = PerfectHash(contracts, PHF_SIZE, key=lambda entry: entry.contract)

    contract_phf = PerfectHash(

        contracts, PHF_SIZE, key=lambda entry: entry.contract.encode()

    )



    js_services_phf = PerfectHash(

        list(js_services.values()), PHF_SIZE, key=lambda entry: entry.js_name

        list(js_services.values()), PHF_SIZE, key=lambda entry: entry.js_name.encode()

    )



    protocol_handlers_phf = PerfectHash(

        list(protocol_handlers.values()), TINY_PHF_SIZE, key=lambda entry: entry.scheme

        list(protocol_handlers.values()),

        TINY_PHF_SIZE,

        key=lambda entry: entry.scheme.encode(),

    )



    js_services_json = {}
@@ -945,7 +949,7 @@ def gen_substs(manifests): 
    substs["contract_count"] = len(contracts)

    substs["protocol_handler_count"] = len(protocol_handlers)



    substs["default_protocol_handler_idx"] = protocol_handlers_phf.get_index("default")

    substs["default_protocol_handler_idx"] = protocol_handlers_phf.get_index(b"default")



    gen_module_funcs(substs, module_funcs)

xpcom/ds/tools/perfecthash.py

+10 −21
Original line number Diff line number Diff line
@@ -24,18 +24,6 @@ small dataset it was designed for. In the future we may want to optimize further 
import textwrap

from collections import namedtuple



import six

from mozbuild.util import ensure_bytes





# Iteration over bytestrings works differently in Python 2 and 3; this function

# captures the two possibilities. Returns an 'int' given the output of iterating

# through a bytestring regardless of the input.

def _ord(c):

    if six.PY3:

        return c

    return ord(c)





class PerfectHash(object):

    """PerfectHash objects represent a computed perfect hash function, which
@@ -88,7 +76,7 @@ class PerfectHash(object): 


        for bucket in buckets:

            # Once we've reached an empty bucket, we're done.

            if len(bucket.entries) == 0:

            if not bucket.entries:

                break



            # Try values for the basis until we find one with no conflicts.
@@ -103,7 +91,7 @@ class PerfectHash(object): 
                    # There was a conflict, try the next basis.

                    basis += 1

                    idx = 0

                    del slots[:]

                    slots.clear()

                    assert basis < self.U32_MAX, "table too small"

                else:

                    slots.append(slot)
@@ -127,15 +115,16 @@ class PerfectHash(object): 
        32-bit FNV is used for indexing into the first table, and the value

        stored in that table is used as the offset basis for indexing into the

        values table."""

        for byte in memoryview(ensure_bytes(key)):

            obyte = _ord(byte)

        FNV_PRIME = cls.FNV_PRIME

        U32_MAX = cls.U32_MAX

        for obyte in memoryview(key):

            basis ^= obyte  # xor-in the byte

            basis *= cls.FNV_PRIME  # Multiply by the FNV prime

            basis &= cls.U32_MAX  # clamp to 32-bits

            basis *= FNV_PRIME  # Multiply by the FNV prime

            basis &= U32_MAX  # clamp to 32-bits

        return basis



    def key(self, entry):

        return memoryview(ensure_bytes(self._key(entry)))

        return memoryview(self._key(entry))



    def get_raw_index(self, key):

        """Determine the index in self.entries without validating"""
@@ -145,7 +134,7 @@ class PerfectHash(object): 
    def get_index(self, key):

        """Given a key, determine the index in self.entries"""

        idx = self.get_raw_index(key)

        if memoryview(ensure_bytes(key)) != self.key(self.entries[idx]):

        if memoryview(key) != self.key(self.entries[idx]):

            return None

        return idx
@@ -334,7 +323,7 @@ class CGHelper(object): 
                            not in the table."""



        assert all(

            _ord(b) <= 0x7F for e in self.phf.entries for b in self.phf.key(e)

            b <= 0x7F for e in self.phf.entries for b in self.phf.key(e)

        ), "non-ASCII key"



        if return_type is None: