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git/t/t0011-hashmap.sh
Karsten Blees 6a364ced49 add a hashtable implementation that supports O(1) removal
The existing hashtable implementation (in hash.[ch]) uses open addressing
(i.e. resolve hash collisions by distributing entries across the table).
Thus, removal is difficult to implement with less than O(n) complexity.
Resolving collisions of entries with identical hashes (e.g. via chaining)
is left to the client code.

Add a hashtable implementation that supports O(1) removal and is slightly
easier to use due to builtin entry chaining.

Supports all basic operations init, free, get, add, remove and iteration.

Also includes ready-to-use hash functions based on the public domain FNV-1
algorithm (http://www.isthe.com/chongo/tech/comp/fnv).

The per-entry data structure (hashmap_entry) is piggybacked in front of
the client's data structure to save memory. See test-hashmap.c for usage
examples.

The hashtable is resized by a factor of four when 80% full. With these
settings, average memory consumption is about 2/3 of hash.[ch], and
insertion is about twice as fast due to less frequent resizing.

Lookups are also slightly faster, because entries are strictly confined to
their bucket (i.e. no data of other buckets needs to be traversed).

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-11-18 13:03:51 -08:00

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#!/bin/sh
test_description='test hashmap and string hash functions'
. ./test-lib.sh
test_hashmap() {
echo "$1" | test-hashmap $3 > actual &&
echo "$2" > expect &&
test_cmp expect actual
}
test_expect_success 'hash functions' '
test_hashmap "hash key1" "2215982743 2215982743 116372151 116372151" &&
test_hashmap "hash key2" "2215982740 2215982740 116372148 116372148" &&
test_hashmap "hash fooBarFrotz" "1383912807 1383912807 3189766727 3189766727" &&
test_hashmap "hash foobarfrotz" "2862305959 2862305959 3189766727 3189766727"
'
test_expect_success 'put' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
put foobarfrotz value4
size" "NULL
NULL
NULL
NULL
64 4"
'
test_expect_success 'put (case insensitive)' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
size" "NULL
NULL
NULL
64 3" ignorecase
'
test_expect_success 'replace' '
test_hashmap "put key1 value1
put key1 value2
put fooBarFrotz value3
put fooBarFrotz value4
size" "NULL
value1
NULL
value3
64 2"
'
test_expect_success 'replace (case insensitive)' '
test_hashmap "put key1 value1
put Key1 value2
put fooBarFrotz value3
put foobarfrotz value4
size" "NULL
value1
NULL
value3
64 2" ignorecase
'
test_expect_success 'get' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
put foobarfrotz value4
get key1
get key2
get fooBarFrotz
get notInMap" "NULL
NULL
NULL
NULL
value1
value2
value3
NULL"
'
test_expect_success 'get (case insensitive)' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
get Key1
get keY2
get foobarfrotz
get notInMap" "NULL
NULL
NULL
value1
value2
value3
NULL" ignorecase
'
test_expect_success 'add' '
test_hashmap "add key1 value1
add key1 value2
add fooBarFrotz value3
add fooBarFrotz value4
get key1
get fooBarFrotz
get notInMap" "value2
value1
value4
value3
NULL"
'
test_expect_success 'add (case insensitive)' '
test_hashmap "add key1 value1
add Key1 value2
add fooBarFrotz value3
add foobarfrotz value4
get key1
get Foobarfrotz
get notInMap" "value2
value1
value4
value3
NULL" ignorecase
'
test_expect_success 'remove' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
remove key1
remove key2
remove notInMap
size" "NULL
NULL
NULL
value1
value2
NULL
64 1"
'
test_expect_success 'remove (case insensitive)' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
remove Key1
remove keY2
remove notInMap
size" "NULL
NULL
NULL
value1
value2
NULL
64 1" ignorecase
'
test_expect_success 'iterate' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
iterate" "NULL
NULL
NULL
key2 value2
key1 value1
fooBarFrotz value3"
'
test_expect_success 'iterate (case insensitive)' '
test_hashmap "put key1 value1
put key2 value2
put fooBarFrotz value3
iterate" "NULL
NULL
NULL
fooBarFrotz value3
key2 value2
key1 value1" ignorecase
'
test_expect_success 'grow / shrink' '
rm -f in &&
rm -f expect &&
for n in $(test_seq 51)
do
echo put key$n value$n >> in &&
echo NULL >> expect
done &&
echo size >> in &&
echo 64 51 >> expect &&
echo put key52 value52 >> in &&
echo NULL >> expect
echo size >> in &&
echo 256 52 >> expect &&
for n in $(test_seq 12)
do
echo remove key$n >> in &&
echo value$n >> expect
done &&
echo size >> in &&
echo 256 40 >> expect &&
echo remove key40 >> in &&
echo value40 >> expect &&
echo size >> in &&
echo 64 39 >> expect &&
cat in | test-hashmap > out &&
test_cmp expect out
'
test_done