NAME
Data::HashMap - Fast type-specialized hash maps implemented in C
SYNOPSIS
use Data::HashMap::II;
# Keyword API (fastest - bypasses method dispatch)
my $map = Data::HashMap::II->new();
hm_ii_put $map, 42, 100;
my $val = hm_ii_get $map, 42; # 100
hm_ii_exists $map, 42; # true
hm_ii_remove $map, 42;
# Method API (convenient - same operations)
$map->put(42, 100);
my $val = $map->get(42); # 100
$map->exists(42); # true
$map->remove(42);
# Counter operations (integer-value variants only)
my $count = hm_ii_incr $map, 1; # 1
$count = hm_ii_incr $map, 1; # 2
$count = hm_ii_decr $map, 1; # 1
# Iteration
my @keys = hm_ii_keys $map;
my @values = hm_ii_values $map;
my @pairs = hm_ii_items $map; # (k1, v1, k2, v2, ...)
while (my ($k, $v) = hm_ii_each $map) { ... }
# Bulk operations
my $href = hm_ii_to_hash $map; # Perl hashref snapshot
hm_ii_clear $map; # remove all entries
# LRU cache (max 1000 entries, evicts least-recently-used)
my $lru = Data::HashMap::II->new(1000);
# TTL cache (entries expire after 60 seconds)
my $ttl = Data::HashMap::II->new(0, 60);
# LRU + TTL combined
my $both = Data::HashMap::II->new(1000, 60);
# Per-key TTL
hm_ii_put_ttl $map, 42, 100, 30; # expires in 30 seconds
# Get or set default
my $v = hm_ii_get_or_set $map, 99, 0; # insert 0 if key 99 absentDESCRIPTION
Data::HashMap provides fourteen type-specialized hash map implementations in C, each optimized for its specific key/value type combination. All data access uses keyword syntax, which bypasses Perl's method dispatch for maximum performance. A method-call API ($map->get($key)) is also available for convenience.
Keywords are automatically enabled when you use a variant module.
VARIANTS
- Data::HashMap::I16 - int16 keys, int16 values (4 bytes/entry)
- Data::HashMap::I16A - int16 keys, any Perl SV* values (refs, objects, etc.)
- Data::HashMap::I16S - int16 keys, string values
- Data::HashMap::I32 - int32 keys, int32 values (8 bytes/entry)
- Data::HashMap::I32A - int32 keys, any Perl SV* values (refs, objects, etc.)
- Data::HashMap::I32S - int32 keys, string values
- Data::HashMap::II - int64 keys, int64 values (16 bytes/entry)
- Data::HashMap::IA - int64 keys, any Perl SV* values (refs, objects, etc.)
- Data::HashMap::IS - int64 keys, string values
- Data::HashMap::SA - string keys, any Perl SV* values (refs, objects, etc.)
- Data::HashMap::SI16 - string keys, int16 values
- Data::HashMap::SI32 - string keys, int32 values
- Data::HashMap::SI - string keys, int64 values
- Data::HashMap::SS - string keys, string values
KEYWORDS
Each variant provides the following keywords (replace xx with the variant prefix: i16, i16a, i16s, i32, i32a, i32s, ia, ii, is, sa, si16, si32, si, ss):
hm_xx_put $map, $key, $value # insert/update, returns bool
hm_xx_get $map, $key # lookup, returns value or undef
hm_xx_exists $map, $key # returns bool
hm_xx_remove $map, $key # returns bool
hm_xx_size $map # returns entry count (includes TTL-expired not yet reaped)
# List-returning:
hm_xx_keys $map # returns list of keys
hm_xx_values $map # returns list of values
hm_xx_items $map # returns (k1,v1, k2,v2, ...)Integer-value variants (I16, I32, II, SI16, SI32, SI) also provide:
hm_xx_incr $map, $key # +1, returns new value (new keys init to 0)
hm_xx_decr $map, $key # -1, returns new value (new keys init to 0)
hm_xx_incr_by $map, $key, $n # +N, returns new value (new keys init to 0)All variants also provide:
hm_xx_max_size $map # returns max_size (0 = no LRU)
hm_xx_ttl $map # returns default TTL in seconds (0 = no TTL)
hm_xx_clear $map # remove all entries
hm_xx_to_hash $map # returns a Perl hashref snapshot
hm_xx_each $map # returns (key, value) or empty list
hm_xx_iter_reset $map # reset each() iterator to start
hm_xx_put_ttl $map, $key, $val, $seconds # insert with per-key TTL ($seconds=0 uses map default)
hm_xx_get_or_set $map, $key, $default # get existing or insert defaultString-value variants (SS, IS, I32S, I16S) also provide:
hm_xx_get_direct $map, $key # zero-copy get (read-only, see CAVEATS)CONSTRUCTOR
my $map = Data::HashMap::II->new(); # plain (no LRU, no TTL)
my $lru = Data::HashMap::II->new(1000); # LRU: max 1000 entries
my $ttl = Data::HashMap::II->new(0, 60); # TTL: 60-second expiry
my $both = Data::HashMap::II->new(1000, 60); # LRU + TTLLRU eviction
When max_size is set, the map acts as an LRU cache. Inserting beyond capacity evicts the least-recently-used entry. get, put (update), and counter operations promote the accessed entry to most-recently-used.
TTL expiry
When default_ttl is set (in seconds), entries expire lazily: expired entries are removed on access (get, exists, counter ops) and skipped during iteration (keys, values, items, each, to_hash). Note that hm_xx_size returns the count of all inserted entries including those past their TTL that have not yet been lazily removed. exists does not promote entries in LRU mode (read-only check). get_or_set inserts with the map's default TTL; per-key TTL is not supported via get_or_set (use put_ttl for that).
Individual entries can also be given a per-key TTL via hm_xx_put_ttl or $map->put_ttl($key, $value, $seconds), even on maps created without a default TTL. The expires array is lazily allocated on first use.
Both features use parallel arrays indexed by slot, keeping the core node struct unchanged. Maps created without LRU/TTL have zero overhead beyond a never-taken branch.
PERFORMANCE
Benchmarks with 100k entries on Linux x86_64 (higher is better):
INSERT (iterations/sec):
Rate perl_ss perl_ii SA SS IA I32A SI32 SI IS I32S I32 II I16S SI16 I16A I16
perl_ss 17.6/s -- -1% -11% -27% -45% -48% -51% -53% -54% -55% -83% -83% -86% -86% -88% -96%
perl_ii 17.7/s 1% -- -11% -26% -45% -48% -51% -53% -54% -54% -82% -83% -86% -86% -87% -96%
SA 19.8/s 12% 12% -- -18% -38% -42% -45% -47% -48% -49% -80% -81% -84% -84% -86% -95%
SS 24.1/s 37% 36% 22% -- -25% -29% -33% -36% -37% -38% -76% -77% -81% -81% -83% -94%
IA 32.0/s 82% 81% 62% 33% -- -6% -11% -15% -16% -17% -68% -70% -75% -75% -77% -92%
I32A 34.0/s 93% 92% 72% 41% 6% -- -5% -10% -11% -13% -66% -68% -73% -73% -76% -92%
SI32 35.9/s 104% 103% 81% 49% 12% 6% -- -5% -6% -8% -64% -66% -72% -72% -75% -91%
SI 37.6/s 113% 112% 90% 56% 17% 11% 5% -- -2% -3% -63% -65% -70% -70% -73% -91%
IS 38.3/s 118% 116% 93% 59% 20% 13% 7% 2% -- -1% -62% -64% -70% -70% -73% -91%
I32S 38.8/s 121% 119% 96% 61% 21% 14% 8% 3% 1% -- -61% -63% -69% -69% -73% -90%
I32 101/s 472% 468% 408% 318% 214% 196% 180% 168% 163% 159% -- -5% -20% -20% -29% -75%
II 106/s 501% 498% 435% 339% 230% 212% 195% 182% 176% 173% 5% -- -16% -16% -25% -74%
I16S 126/s 618% 614% 538% 425% 295% 272% 252% 236% 230% 226% 26% 19% -- -0% -11% -69%
SI16 126/s 618% 614% 538% 425% 295% 272% 252% 236% 230% 226% 26% 19% 0% -- -11% -69%
I16A 141/s 703% 698% 614% 487% 341% 316% 294% 276% 269% 264% 40% 34% 12% 12% -- -65%
I16 404/s 2196% 2182% 1941% 1577% 1161% 1090% 1027% 976% 955% 941% 302% 282% 220% 220% 186% --
LOOKUP (iterations/sec):
Rate SS_direct perl_ii SS SA perl_ss SI SI32 IS I32S I32A IS_direct IA II I32 SI16 I16A I16S I16
SS_direct 26.0/s -- -15% -17% -18% -21% -30% -31% -43% -49% -54% -54% -60% -68% -76% -84% -86% -90% -93%
perl_ii 30.5/s 17% -- -2% -4% -8% -18% -19% -34% -40% -46% -47% -53% -62% -72% -81% -84% -88% -92%
SS 31.3/s 20% 3% -- -1% -6% -16% -16% -32% -38% -44% -45% -52% -61% -72% -81% -83% -88% -92%
SA 31.7/s 22% 4% 1% -- -4% -15% -15% -31% -38% -44% -45% -51% -61% -71% -80% -83% -88% -92%
perl_ss 33.1/s 27% 9% 6% 5% -- -11% -12% -28% -35% -41% -42% -49% -59% -70% -79% -82% -87% -91%
SI 37.2/s 43% 22% 19% 17% 12% -- -1% -19% -27% -34% -35% -43% -54% -66% -77% -80% -85% -90%
SI32 37.5/s 44% 23% 20% 18% 13% 1% -- -19% -26% -33% -34% -42% -54% -66% -77% -80% -85% -90%
IS 46.0/s 77% 51% 47% 45% 39% 24% 23% -- -9% -18% -20% -29% -43% -58% -71% -75% -82% -88%
I32S 50.7/s 95% 66% 62% 60% 53% 36% 35% 10% -- -10% -11% -22% -37% -54% -69% -73% -80% -86%
I32A 56.3/s 116% 85% 80% 78% 70% 51% 50% 22% 11% -- -2% -13% -30% -49% -65% -70% -78% -85%
IS_direct 57.2/s 120% 87% 83% 80% 73% 54% 53% 24% 13% 2% -- -12% -29% -48% -65% -69% -78% -85%
IA 64.7/s 149% 112% 107% 104% 95% 74% 73% 41% 28% 15% 13% -- -20% -42% -60% -65% -75% -83%
II 80.8/s 210% 165% 158% 155% 144% 117% 116% 76% 59% 43% 41% 25% -- -27% -50% -57% -68% -78%
I32 111/s 325% 263% 254% 249% 234% 198% 196% 141% 118% 97% 94% 71% 37% -- -31% -41% -57% -71%
SI16 161/s 520% 428% 415% 409% 387% 334% 331% 250% 218% 186% 182% 149% 100% 46% -- -13% -37% -57%
I16A 186/s 615% 510% 495% 487% 462% 401% 397% 305% 267% 231% 226% 188% 130% 68% 15% -- -27% -50%
I16S 256/s 885% 740% 719% 709% 674% 589% 584% 457% 405% 355% 348% 296% 217% 132% 59% 38% -- -32%
I16 375/s 1342% 1130% 1100% 1084% 1033% 910% 902% 716% 640% 566% 556% 480% 365% 239% 133% 102% 46% --
INCREMENT (iterations/sec):
Rate perl_ss perl_ii SI32 SI I32 II SI16 I16
perl_ss 26.2/s -- -5% -12% -15% -64% -65% -77% -90%
perl_ii 27.6/s 5% -- -8% -10% -62% -63% -76% -89%
SI32 30.0/s 14% 9% -- -3% -59% -60% -73% -88%
SI 30.7/s 17% 12% 3% -- -58% -59% -73% -88%
I32 73.1/s 179% 165% 144% 138% -- -2% -35% -71%
II 74.4/s 184% 170% 148% 142% 2% -- -34% -71%
SI16 113/s 330% 310% 277% 267% 54% 52% -- -56%
I16 255/s 871% 824% 750% 728% 248% 242% 126% --
DELETE (iterations/sec):
Rate SA SS IS SI32 SI perl_ss I32S IA perl_ii I32A II I32 SI16 I16A I16S I16
SA 10.9/s -- -6% -18% -25% -25% -27% -32% -32% -36% -41% -58% -76% -83% -84% -86% -93%
SS 11.6/s 6% -- -13% -20% -21% -22% -27% -28% -32% -37% -55% -74% -82% -83% -85% -93%
IS 13.3/s 22% 14% -- -9% -9% -11% -17% -17% -23% -28% -48% -70% -80% -81% -83% -92%
SI32 14.6/s 33% 25% 9% -- -0% -2% -9% -10% -15% -21% -44% -68% -78% -79% -81% -91%
SI 14.6/s 34% 26% 10% 0% -- -2% -8% -9% -15% -21% -43% -68% -78% -79% -81% -91%
perl_ss 14.9/s 36% 28% 12% 2% 2% -- -7% -8% -13% -19% -42% -67% -77% -78% -81% -91%
I32S 16.0/s 46% 37% 20% 10% 9% 7% -- -1% -7% -14% -38% -65% -76% -77% -80% -90%
IA 16.1/s 47% 38% 21% 11% 10% 8% 1% -- -6% -13% -38% -64% -76% -76% -79% -90%
perl_ii 17.2/s 57% 48% 29% 18% 18% 16% 8% 7% -- -7% -33% -62% -74% -75% -78% -90%
I32A 18.5/s 69% 59% 39% 27% 26% 24% 16% 15% 7% -- -28% -59% -72% -73% -76% -89%
II 25.8/s 136% 122% 94% 77% 77% 73% 62% 60% 50% 40% -- -43% -61% -62% -67% -84%
I32 45.1/s 313% 288% 239% 210% 208% 203% 182% 180% 162% 144% 75% -- -32% -34% -42% -73%
SI16 65.9/s 503% 467% 395% 353% 351% 343% 313% 310% 283% 257% 155% 46% -- -3% -15% -60%
I16A 68.3/s 525% 487% 413% 369% 367% 359% 328% 324% 297% 270% 164% 51% 4% -- -12% -58%
I16S 78.0/s 614% 571% 486% 436% 433% 424% 388% 384% 353% 322% 202% 73% 18% 14% -- -53%
I16 165/s 1406% 1315% 1136% 1030% 1025% 1005% 930% 922% 856% 791% 537% 265% 150% 141% 111% --LRU / TTL overhead
LRU and TTL add parallel arrays for linked-list pointers and expiry timestamps. Maps created without these features have zero overhead beyond a never-taken branch.
INSERT, II variant (iterations/sec):
Rate II_lru II_lru_ttl II
II_lru 68.8/s -- -2% -16%
II_lru_ttl 70.4/s 2% -- -14%
II 81.9/s 19% 16% --
LOOKUP, II variant (iterations/sec):
Rate II_lru_ttl II_lru II
II_lru_ttl 68.3/s -- -14% -33%
II_lru 79.3/s 16% -- -23%
II 103/s 50% 29% --
LRU EVICTION CHURN: insert 100k into capacity 50k (iterations/sec):
Rate II_lru_ttl II_lru
II_lru_ttl 61.7/s -- -13%
II_lru 71.0/s 15% --Method vs keyword overhead
Keywords bypass Perl's method dispatch for maximum performance. Method calls ($map->get($key)) are convenient but slower:
II variant, 100k operations (iterations/sec):
keyword method overhead
LOOKUP 85.5/s 59.1/s -31%
INSERT 71.1/s 59.0/s -17%MEMORY
Memory usage with 1M entries (fork-isolated measurements):
Variant Memory Bytes/entry vs Perl hash
------- ------ ----------- ------------
I16* 0.5 MB 16 10x less
I32 29 MB 30 5.5x less
II 45 MB 46 3.5x less
I32S 73 MB 75 2.2x less
IS 73 MB 75 2.2x less
SI16 73 MB 75 2.2x less
SI32 73 MB 75 2.2x less
SI 73 MB 75 2.2x less
I16A 0.5 MB 16 10x less
I32A 92 MB 95 1.7x less
IA 92 MB 95 1.7x less
SS 121 MB 124 1.3x less
SA 140 MB 144 1.1x less
perl %h (int) 159 MB 163 (baseline)
perl %h (str) 166 MB 170 (baseline)
* I16/I16A/I16S measured at 30k entries (int16 key range limits max unique keys to ~65k)LRU / TTL memory overhead
Overhead per entry for LRU (prev/next pointers) and TTL (expiry timestamp), measured with 1M entries in fork-isolated processes.
II variant (int64/int64):
Variant Bytes/entry LRU overhead +TTL overhead
------- ----------- ------------ -------------
II 46.4 - -
II_lru 67.3 +20.9 B -
II_lru_ttl 79.9 - +12.6 B
SS variant (string/string, various key+value sizes):
Variant Bytes/entry LRU overhead +TTL overhead
------- ----------- ------------ -------------
SS 8B keys 123.9 - -
SS 8B lru 140.7 +16.8 B -
SS 8B lru+ttl 152.2 - +11.5 B
SS 16B keys 123.9 - -
SS 16B lru 140.7 +16.8 B -
SS 16B lru+ttl 152.2 - +11.5 B
SS 32B keys 155.9 - -
SS 32B lru 172.7 +16.8 B -
SS 32B lru+ttl 181.1 - +8.4 B
SS 64B keys 220.0 - -
SS 64B lru 236.7 +16.8 B -
SS 64B lru+ttl 245.1 - +8.4 BIMPLEMENTATION
Open addressing with linear probing
xxHash v0.8.3 (XXH3_64bits) hash functions for both integer and string keys
Automatic resize at 75% load factor
Tombstone deletion with automatic compaction
Raw C strings (no Perl SV overhead) for string storage
UTF-8 flag packed into high bit of length fields; keys with different UTF-8 flags are treated as distinct even if bytes match
Sentinel values for integer keys (INT_MIN, INT_MIN+1 are reserved and silently rejected). I16/I32 variants croak on out-of-range keys and values.
each()iterator resets ifput/remove/incr/get_or_settriggers a resize or compaction; do not mutate the map duringeach()iteration. In scalar context,$map->eachreturns the key only; the keyword formhm_xx_eachalways evaluates in list context (XS::Parse::Keyword limitation).Requires 64-bit Perl (
use64bitint); II/IS/IA/SI variants use int64 keys/values via IVget_directreturns a read-only SV pointing at the map's internal buffer (zero-copy, no malloc). The returned value must not be held past any map mutation (put,remove,clear, or any operation that may resize). Safe for immediate use: comparisons, printing, passing to functions. Useget(the default) when you need to store the value.
DEPENDENCIES
XS::Parse::Keyword (>= 0.40)
AUTHOR
vividsnow
LICENSE
This is free software; you can redistribute it and/or modify it under the same terms as Perl itself.