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module: fix potential archetype hash collision lookup issues

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2024-05-26 18:03:57 -07:00
parent b6a7296251
commit 13ff5097db
1 changed files with 12 additions and 1 deletions
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13
src/module/entities.zig
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@ -196,7 +196,15 @@ pub fn Database(comptime modules: anytype) type {
if (entities.buckets[bucket_index]) |bucket| { if (entities.buckets[bucket_index]) |bucket| {
// Bucket already exists // Bucket already exists
var archetype = &entities.archetypes.items[bucket]; var archetype = &entities.archetypes.items[bucket];
if (archetype.next) |_| { var archetype_index: usize = bucket;
if (archetype.next != null) {
if (archetype.hash == hash) {
// Probably a match
// TODO: technically a hash collision could occur here, so maybe check
// column IDs are equal here too?
return .{ .found_existing = true, .hash = hash, .index = bucket, .ptr = archetype };
}
// Multiple archetypes in bucket (there were collisions) // Multiple archetypes in bucket (there were collisions)
while (archetype.next) |collision_index| { while (archetype.next) |collision_index| {
const collision = &entities.archetypes.items[collision_index]; const collision = &entities.archetypes.items[collision_index];
@ -207,10 +215,12 @@ pub fn Database(comptime modules: anytype) type {
return .{ .found_existing = true, .hash = hash, .index = collision_index, .ptr = collision }; return .{ .found_existing = true, .hash = hash, .index = collision_index, .ptr = collision };
} }
archetype = collision; archetype = collision;
archetype_index = collision_index;
} }
// New collision // New collision
try entities.archetypes.append(entities.allocator, undefined); try entities.archetypes.append(entities.allocator, undefined);
archetype = &entities.archetypes.items[archetype_index]; // handle potential pointer invalidation
const index = entities.archetypes.items.len - 1; const index = entities.archetypes.items.len - 1;
const ptr = &entities.archetypes.items[index]; const ptr = &entities.archetypes.items[index];
archetype.next = @intCast(index); archetype.next = @intCast(index);
@ -222,6 +232,7 @@ pub fn Database(comptime modules: anytype) type {
// New collision // New collision
try entities.archetypes.append(entities.allocator, undefined); try entities.archetypes.append(entities.allocator, undefined);
archetype = &entities.archetypes.items[archetype_index]; // handle potential pointer invalidation
const index = entities.archetypes.items.len - 1; const index = entities.archetypes.items.len - 1;
const ptr = &entities.archetypes.items[index]; const ptr = &entities.archetypes.items[index];
archetype.next = @intCast(index); archetype.next = @intCast(index);