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std.ArrayHashMap: base linear_scan_max on cache line size #22861

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Merged
merged 1 commit into from
Feb 12, 2025
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std.ArrayHashMap: base linear_scan_max on cache line size #22861

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11 changes: 7 additions & 4 deletions lib/std/array_hash_map.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -605,7 +605,10 @@ pub fn ArrayHashMapUnmanaged(

const Self = @This();

const linear_scan_max = 8;
const linear_scan_max = @as(comptime_int, @max(1, @as(comptime_int, @min(
std.atomic.cache_line / @as(comptime_int, @max(1, @sizeOf(Hash))),
std.atomic.cache_line / @as(comptime_int, @max(1, @sizeOf(K))),
))));

const RemovalType = enum {
swap,
Expand Down Expand Up @@ -2376,7 +2379,7 @@ test "shrink" {
defer map.deinit();

// This test is more interesting if we insert enough entries to allocate the index header.
const num_entries = 20;
const num_entries = 200;
var i: i32 = 0;
while (i < num_entries) : (i += 1)
try testing.expect((try map.fetchPut(i, i * 10)) == null);
Expand All @@ -2387,7 +2390,7 @@ test "shrink" {
// Test `shrinkRetainingCapacity`.
map.shrinkRetainingCapacity(17);
try testing.expect(map.count() == 17);
try testing.expect(map.capacity() == 20);
try testing.expect(map.capacity() >= num_entries);
i = 0;
while (i < num_entries) : (i += 1) {
const gop = try map.getOrPut(i);
Expand Down Expand Up @@ -2436,7 +2439,7 @@ test "reIndex" {
defer map.deinit();

// Populate via the API.
const num_indexed_entries = 20;
const num_indexed_entries = 200;
var i: i32 = 0;
while (i < num_indexed_entries) : (i += 1)
try testing.expect((try map.fetchPut(i, i * 10)) == null);
Expand Down
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