Mercurial > hg

changeset 43826:5ac243a92e37

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rust-performance: introduce FastHashMap type alias for HashMap Rust's default hashing is slow, because it is meant for preventing collision attacks. For all of the current Rust code, we don't care about those attacks, because if an person with bad intentions has write access to your repo, you have other issues. I've chosen to use the TwoXHash crate because it was made by a reputable member of the Rust community and has very good benchmarks. For now it does not seem to improve performance by much for the current code, but it's something else to not worry about when benchmarking code: in a previous experiment with copytracing in Rust, it accounted for more than 10% of the time of the entire script. Differential Revision: https://phab.mercurial-scm.org/D7116
author Raphaël Gomès <rgomes@octobus.net>
date Mon, 14 Oct 2019 13:57:30 +0200
parents 8f26dd09aa78
children c27e688fcdc3
files rust/Cargo.lock rust/hg-core/Cargo.toml rust/hg-core/src/dirstate.rs rust/hg-core/src/dirstate/dirs_multiset.rs rust/hg-core/src/dirstate/dirstate_map.rs rust/hg-core/src/dirstate/parsers.rs rust/hg-core/src/discovery.rs rust/hg-core/src/filepatterns.rs rust/hg-core/src/lib.rs rust/hg-cpython/src/parsers.rs
diffstat 10 files changed, 138 insertions(+), 48 deletions(-) [+]
line wrap: on
line diff
--- a/rust/Cargo.lock	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/Cargo.lock	Mon Oct 14 13:57:30 2019 +0200
@@ -32,6 +32,15 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "c2-chacha"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ppv-lite86 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "cfg-if"
 version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -105,6 +114,16 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "getrandom"
+version = "0.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.64 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasi 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "hg-core"
 version = "0.1.0"
 dependencies = [
@@ -115,6 +134,7 @@
  "rand_pcg 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "twox-hash 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -179,6 +199,11 @@
 ]
 
 [[package]]
+name = "ppv-lite86"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "python27-sys"
 version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -215,6 +240,18 @@
 ]
 
 [[package]]
+name = "rand"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "getrandom 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.64 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_chacha 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_hc 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "rand_chacha"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -224,6 +261,15 @@
 ]
 
 [[package]]
+name = "rand_chacha"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "c2-chacha 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "rand_core"
 version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -237,6 +283,14 @@
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "rand_core"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "getrandom 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "rand_hc"
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -245,6 +299,14 @@
 ]
 
 [[package]]
+name = "rand_hc"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "rand_isaac"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -373,6 +435,19 @@
 ]
 
 [[package]]
+name = "twox-hash"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "wasi"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "winapi"
 version = "0.3.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -397,6 +472,7 @@
 "checksum autocfg 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "b671c8fb71b457dd4ae18c4ba1e59aa81793daacc361d82fcd410cef0d491875"
 "checksum bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 "checksum byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a7c3dd8985a7111efc5c80b44e23ecdd8c007de8ade3b96595387e812b957cf5"
+"checksum c2-chacha 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7d64d04786e0f528460fc884753cf8dddcc466be308f6026f8e355c41a0e4101"
 "checksum cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 "checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
 "checksum cpython 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "85532c648315aeb0829ad216a6a29aa3212cf9319bc7f6daf1404aa0bdd1485f"
@@ -406,6 +482,7 @@
 "checksum crossbeam-utils 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)" = "04973fa96e96579258a5091af6003abde64af786b860f18622b82e026cca60e6"
 "checksum either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
 "checksum fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
+"checksum getrandom 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)" = "473a1265acc8ff1e808cd0a1af8cee3c2ee5200916058a2ca113c29f2d903571"
 "checksum lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 "checksum libc 0.2.64 (registry+https://github.com/rust-lang/crates.io-index)" = "74dfca3d9957906e8d1e6a0b641dc9a59848e793f1da2165889fd4f62d10d79c"
 "checksum memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "88579771288728879b57485cc7d6b07d648c9f0141eb955f8ab7f9d45394468e"
@@ -413,13 +490,18 @@
 "checksum nodrop 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
 "checksum num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "6ba9a427cfca2be13aa6f6403b0b7e7368fe982bfa16fccc450ce74c46cd9b32"
 "checksum num_cpus 1.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "bcef43580c035376c0705c42792c294b66974abbfd2789b511784023f71f3273"
+"checksum ppv-lite86 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e3cbf9f658cdb5000fcf6f362b8ea2ba154b9f146a61c7a20d647034c6b6561b"
 "checksum python27-sys 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "372555e88a6bc8109eb641380240dc8d25a128fc48363ec9075664daadffdd5b"
 "checksum python3-sys 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f3a8ebed3f1201fda179f3960609dbbc10cd8c75e9f2afcb03788278f367d8ea"
 "checksum rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)" = "6d71dacdc3c88c1fde3885a3be3fbab9f35724e6ce99467f7d9c5026132184ca"
+"checksum rand 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "3ae1b169243eaf61759b8475a998f0a385e42042370f3a7dbaf35246eacc8412"
 "checksum rand_chacha 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "556d3a1ca6600bfcbab7c7c91ccb085ac7fbbcd70e008a98742e7847f4f7bcef"
+"checksum rand_chacha 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "03a2a90da8c7523f554344f921aa97283eadf6ac484a6d2a7d0212fa7f8d6853"
 "checksum rand_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6fdeb83b075e8266dcc8762c22776f6877a63111121f5f8c7411e5be7eed4b"
 "checksum rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9c33a3c44ca05fa6f1807d8e6743f3824e8509beca625669633be0acbdf509dc"
+"checksum rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "90bde5296fc891b0cef12a6d03ddccc162ce7b2aff54160af9338f8d40df6d19"
 "checksum rand_hc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7b40677c7be09ae76218dc623efbf7b18e34bced3f38883af07bb75630a21bc4"
+"checksum rand_hc 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ca3129af7b92a17112d59ad498c6f81eaf463253766b90396d39ea7a39d6613c"
 "checksum rand_isaac 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ded997c9d5f13925be2a6fd7e66bf1872597f759fd9dd93513dd7e92e5a5ee08"
 "checksum rand_jitter 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "1166d5c91dc97b88d1decc3285bb0a99ed84b05cfd0bc2341bdf2d43fc41e39b"
 "checksum rand_os 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "7b75f676a1e053fc562eafbb47838d67c84801e38fc1ba459e8f180deabd5071"
@@ -435,6 +517,8 @@
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
+"checksum twox-hash 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3bfd5b7557925ce778ff9b9ef90e3ade34c524b5ff10e239c69a42d546d2af56"
+"checksum wasi 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b89c3ce4ce14bdc6fb6beaf9ec7928ca331de5df7e5ea278375642a2f478570d"
 "checksum winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "8093091eeb260906a183e6ae1abdba2ef5ef2257a21801128899c3fc699229c6"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
--- a/rust/hg-core/Cargo.toml	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/Cargo.toml	Mon Oct 14 13:57:30 2019 +0200
@@ -14,5 +14,6 @@
 memchr = "2.2.0"
 rand = "0.6.5"
 rand_pcg = "0.1.1"
+rayon = "1.2.0"
 regex = "1.1.0"
-rayon = "1.2.0"
+twox-hash = "1.5.0"
--- a/rust/hg-core/src/dirstate.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/dirstate.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -5,9 +5,8 @@
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2 or any later version.
 
-use crate::{utils::hg_path::HgPathBuf, DirstateParseError};
+use crate::{utils::hg_path::HgPathBuf, DirstateParseError, FastHashMap};
 use std::collections::hash_map;
-use std::collections::HashMap;
 use std::convert::TryFrom;
 
 pub mod dirs_multiset;
@@ -37,9 +36,9 @@
 /// merge.
 pub const SIZE_FROM_OTHER_PARENT: i32 = -2;
 
-pub type StateMap = HashMap<HgPathBuf, DirstateEntry>;
+pub type StateMap = FastHashMap<HgPathBuf, DirstateEntry>;
 pub type StateMapIter<'a> = hash_map::Iter<'a, HgPathBuf, DirstateEntry>;
-pub type CopyMap = HashMap<HgPathBuf, HgPathBuf>;
+pub type CopyMap = FastHashMap<HgPathBuf, HgPathBuf>;
 pub type CopyMapIter<'a> = hash_map::Iter<'a, HgPathBuf, HgPathBuf>;
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
--- a/rust/hg-core/src/dirstate/dirs_multiset.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/dirstate/dirs_multiset.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -11,16 +11,16 @@
 use crate::utils::hg_path::{HgPath, HgPathBuf};
 use crate::{
     dirstate::EntryState, utils::files, DirstateEntry, DirstateMapError,
+    FastHashMap,
 };
 use std::collections::hash_map::{self, Entry};
-use std::collections::HashMap;
 
 // could be encapsulated if we care API stability more seriously
 pub type DirsMultisetIter<'a> = hash_map::Keys<'a, HgPathBuf, u32>;
 
 #[derive(PartialEq, Debug)]
 pub struct DirsMultiset {
-    inner: HashMap<HgPathBuf, u32>,
+    inner: FastHashMap<HgPathBuf, u32>,
 }
 
 impl DirsMultiset {
@@ -28,11 +28,11 @@
     ///
     /// If `skip_state` is provided, skips dirstate entries with equal state.
     pub fn from_dirstate(
-        vec: &HashMap<HgPathBuf, DirstateEntry>,
+        vec: &FastHashMap<HgPathBuf, DirstateEntry>,
         skip_state: Option<EntryState>,
     ) -> Self {
         let mut multiset = DirsMultiset {
-            inner: HashMap::new(),
+            inner: FastHashMap::default(),
         };
 
         for (filename, DirstateEntry { state, .. }) in vec {
@@ -52,7 +52,7 @@
     /// Initializes the multiset from a manifest.
     pub fn from_manifest(vec: &Vec<HgPathBuf>) -> Self {
         let mut multiset = DirsMultiset {
-            inner: HashMap::new(),
+            inner: FastHashMap::default(),
         };
 
         for filename in vec {
@@ -127,7 +127,6 @@
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::collections::HashMap;
 
     #[test]
     fn test_delete_path_path_not_found() {
@@ -243,13 +242,13 @@
     fn test_dirsmultiset_new_empty() {
         let new = DirsMultiset::from_manifest(&vec![]);
         let expected = DirsMultiset {
-            inner: HashMap::new(),
+            inner: FastHashMap::default(),
         };
         assert_eq!(expected, new);
 
-        let new = DirsMultiset::from_dirstate(&HashMap::new(), None);
+        let new = DirsMultiset::from_dirstate(&FastHashMap::default(), None);
         let expected = DirsMultiset {
-            inner: HashMap::new(),
+            inner: FastHashMap::default(),
         };
         assert_eq!(expected, new);
     }
--- a/rust/hg-core/src/dirstate/dirstate_map.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/dirstate/dirstate_map.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -13,16 +13,16 @@
         hg_path::{HgPath, HgPathBuf},
     },
     CopyMap, DirsMultiset, DirstateEntry, DirstateError, DirstateMapError,
-    DirstateParents, DirstateParseError, StateMap,
+    DirstateParents, DirstateParseError, FastHashMap, StateMap,
 };
 use core::borrow::Borrow;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashSet;
 use std::convert::TryInto;
 use std::iter::FromIterator;
 use std::ops::Deref;
 use std::time::Duration;
 
-pub type FileFoldMap = HashMap<HgPathBuf, HgPathBuf>;
+pub type FileFoldMap = FastHashMap<HgPathBuf, HgPathBuf>;
 
 const NULL_ID: [u8; 20] = [0; 20];
 const MTIME_UNSET: i32 = -1;
@@ -327,7 +327,7 @@
         if let Some(ref file_fold_map) = self.file_fold_map {
             return file_fold_map;
         }
-        let mut new_file_fold_map = FileFoldMap::new();
+        let mut new_file_fold_map = FileFoldMap::default();
         for (filename, DirstateEntry { state, .. }) in self.state_map.borrow()
         {
             if *state == EntryState::Removed {
--- a/rust/hg-core/src/dirstate/parsers.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/dirstate/parsers.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -157,13 +157,12 @@
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::utils::hg_path::HgPathBuf;
-    use std::collections::HashMap;
+    use crate::{utils::hg_path::HgPathBuf, FastHashMap};
 
     #[test]
     fn test_pack_dirstate_empty() {
-        let mut state_map: StateMap = HashMap::new();
-        let copymap = HashMap::new();
+        let mut state_map: StateMap = FastHashMap::default();
+        let copymap = FastHashMap::default();
         let parents = DirstateParents {
             p1: *b"12345678910111213141",
             p2: *b"00000000000000000000",
@@ -194,7 +193,7 @@
         .collect();
         let mut state_map = expected_state_map.clone();
 
-        let copymap = HashMap::new();
+        let copymap = FastHashMap::default();
         let parents = DirstateParents {
             p1: *b"12345678910111213141",
             p2: *b"00000000000000000000",
@@ -230,7 +229,7 @@
         .cloned()
         .collect();
         let mut state_map = expected_state_map.clone();
-        let mut copymap = HashMap::new();
+        let mut copymap = FastHashMap::default();
         copymap.insert(
             HgPathBuf::from_bytes(b"f1"),
             HgPathBuf::from_bytes(b"copyname"),
@@ -270,7 +269,7 @@
         .iter()
         .cloned()
         .collect();
-        let mut copymap = HashMap::new();
+        let mut copymap = FastHashMap::default();
         copymap.insert(
             HgPathBuf::from_bytes(b"f1"),
             HgPathBuf::from_bytes(b"copyname"),
@@ -284,8 +283,8 @@
             pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
                 .unwrap();
 
-        let mut new_state_map: StateMap = HashMap::new();
-        let mut new_copy_map: CopyMap = HashMap::new();
+        let mut new_state_map: StateMap = FastHashMap::default();
+        let mut new_copy_map: CopyMap = FastHashMap::default();
         let new_parents = parse_dirstate(
             &mut new_state_map,
             &mut new_copy_map,
@@ -341,7 +340,7 @@
         .iter()
         .cloned()
         .collect();
-        let mut copymap = HashMap::new();
+        let mut copymap = FastHashMap::default();
         copymap.insert(
             HgPathBuf::from_bytes(b"f1"),
             HgPathBuf::from_bytes(b"copyname"),
@@ -359,8 +358,8 @@
             pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
                 .unwrap();
 
-        let mut new_state_map: StateMap = HashMap::new();
-        let mut new_copy_map: CopyMap = HashMap::new();
+        let mut new_state_map: StateMap = FastHashMap::default();
+        let mut new_copy_map: CopyMap = FastHashMap::default();
         let new_parents = parse_dirstate(
             &mut new_state_map,
             &mut new_copy_map,
@@ -388,7 +387,7 @@
         .iter()
         .cloned()
         .collect();
-        let mut copymap = HashMap::new();
+        let mut copymap = FastHashMap::default();
         copymap.insert(
             HgPathBuf::from_bytes(b"f1"),
             HgPathBuf::from_bytes(b"copyname"),
@@ -402,8 +401,8 @@
             pack_dirstate(&mut state_map, &copymap, parents.clone(), now)
                 .unwrap();
 
-        let mut new_state_map: StateMap = HashMap::new();
-        let mut new_copy_map: CopyMap = HashMap::new();
+        let mut new_state_map: StateMap = FastHashMap::default();
+        let mut new_copy_map: CopyMap = FastHashMap::default();
         let new_parents = parse_dirstate(
             &mut new_state_map,
             &mut new_copy_map,
--- a/rust/hg-core/src/discovery.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/discovery.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -11,12 +11,11 @@
 //! `mercurial.setdiscovery`
 
 use super::{Graph, GraphError, Revision, NULL_REVISION};
-use crate::ancestors::MissingAncestors;
-use crate::dagops;
+use crate::{ancestors::MissingAncestors, dagops, FastHashMap};
 use rand::seq::SliceRandom;
 use rand::{thread_rng, RngCore, SeedableRng};
 use std::cmp::{max, min};
-use std::collections::{HashMap, HashSet, VecDeque};
+use std::collections::{HashSet, VecDeque};
 
 type Rng = rand_pcg::Pcg32;
 
@@ -25,7 +24,7 @@
     graph: G, // plays the role of self._repo
     common: MissingAncestors<G>,
     undecided: Option<HashSet<Revision>>,
-    children_cache: Option<HashMap<Revision, Vec<Revision>>>,
+    children_cache: Option<FastHashMap<Revision, Vec<Revision>>>,
     missing: HashSet<Revision>,
     rng: Rng,
     respect_size: bool,
@@ -61,7 +60,7 @@
 where
     I: Iterator<Item = Revision>,
 {
-    let mut distances: HashMap<Revision, u32> = HashMap::new();
+    let mut distances: FastHashMap<Revision, u32> = FastHashMap::default();
     let mut visit: VecDeque<Revision> = heads.into_iter().collect();
     let mut factor: u32 = 1;
     let mut seen: HashSet<Revision> = HashSet::new();
@@ -328,7 +327,8 @@
         }
         self.ensure_undecided()?;
 
-        let mut children: HashMap<Revision, Vec<Revision>> = HashMap::new();
+        let mut children: FastHashMap<Revision, Vec<Revision>> =
+            FastHashMap::default();
         for &rev in self.undecided.as_ref().unwrap() {
             for p in ParentsIterator::graph_parents(&self.graph, rev)? {
                 children.entry(p).or_insert_with(|| Vec::new()).push(rev);
--- a/rust/hg-core/src/filepatterns.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/filepatterns.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -7,10 +7,11 @@
 
 //! Handling of Mercurial-specific patterns.
 
-use crate::{utils::SliceExt, LineNumber, PatternError, PatternFileError};
+use crate::{
+    utils::SliceExt, FastHashMap, LineNumber, PatternError, PatternFileError,
+};
 use lazy_static::lazy_static;
 use regex::bytes::{NoExpand, Regex};
-use std::collections::HashMap;
 use std::fs::File;
 use std::io::Read;
 use std::path::{Path, PathBuf};
@@ -214,8 +215,8 @@
 }
 
 lazy_static! {
-    static ref SYNTAXES: HashMap<&'static [u8], &'static [u8]> = {
-        let mut m = HashMap::new();
+    static ref SYNTAXES: FastHashMap<&'static [u8], &'static [u8]> = {
+        let mut m = FastHashMap::default();
 
         m.insert(b"re".as_ref(), b"relre:".as_ref());
         m.insert(b"regexp".as_ref(), b"relre:".as_ref());
--- a/rust/hg-core/src/lib.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-core/src/lib.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -24,6 +24,8 @@
 pub use filepatterns::{
     build_single_regex, read_pattern_file, PatternSyntax, PatternTuple,
 };
+use std::collections::HashMap;
+use twox_hash::RandomXxHashBuilder64;
 
 /// Mercurial revision numbers
 ///
@@ -53,6 +55,11 @@
 
 pub type LineNumber = usize;
 
+/// Rust's default hasher is too slow because it tries to prevent collision
+/// attacks. We are not concerned about those: if an ill-minded person has
+/// write access to your repository, you have other issues.
+pub type FastHashMap<K, V> = HashMap<K, V, RandomXxHashBuilder64>;
+
 #[derive(Clone, Debug, PartialEq)]
 pub enum GraphError {
     ParentOutOfRange(Revision),
--- a/rust/hg-cpython/src/parsers.rs	Mon Dec 02 14:44:26 2019 +0100
+++ b/rust/hg-cpython/src/parsers.rs	Mon Oct 14 13:57:30 2019 +0200
@@ -15,9 +15,9 @@
 };
 use hg::{
     pack_dirstate, parse_dirstate, utils::hg_path::HgPathBuf,
-    DirstatePackError, DirstateParents, DirstateParseError, PARENT_SIZE,
+    DirstatePackError, DirstateParents, DirstateParseError, FastHashMap,
+    PARENT_SIZE,
 };
-use std::collections::HashMap;
 use std::convert::TryInto;
 
 use crate::dirstate::{extract_dirstate, make_dirstate_tuple};
@@ -29,8 +29,8 @@
     copymap: PyDict,
     st: PyBytes,
 ) -> PyResult<PyTuple> {
-    let mut dirstate_map = HashMap::new();
-    let mut copies = HashMap::new();
+    let mut dirstate_map = FastHashMap::default();
+    let mut copies = FastHashMap::default();
 
     match parse_dirstate(&mut dirstate_map, &mut copies, st.data(py)) {
         Ok(parents) => {
@@ -85,7 +85,7 @@
 
     let mut dirstate_map = extract_dirstate(py, &dmap)?;
 
-    let copies: Result<HashMap<HgPathBuf, HgPathBuf>, PyErr> = copymap
+    let copies: Result<FastHashMap<HgPathBuf, HgPathBuf>, PyErr> = copymap
         .items(py)
         .iter()
         .map(|(key, value)| {