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module: fix swap removal bug, improve code clarity

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2024-05-09 17:29:51 -07:00
parent 22ac26b57e
commit 10f35a49ef
2 changed files with 27 additions and 103 deletions
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10
src/module/Archetype.zig
View file

@ -82,7 +82,7 @@ pub fn append(storage: *Archetype, gpa: Allocator, row: anytype) !u32 {
storage.len += 1;
storage.setRow(storage.len - 1, row);
return storage.len;
return storage.len - 1;
}
pub fn undoAppend(storage: *Archetype) void {
@ -194,6 +194,7 @@ pub fn getDynamic(storage: *Archetype, row_index: u32, name: StringTable.Index,
/// Swap-removes the specified row with the last row in the table.
pub fn remove(storage: *Archetype, row_index: u32) void {
assert(row_index < storage.len);
if (storage.len > 1 and row_index != storage.len - 1) {
for (storage.columns) |column| {
const dstStart = column.size * row_index;
@ -239,6 +240,13 @@ pub inline fn columnByName(storage: *Archetype, name: StringTable.Index) ?*Colum
return null;
}
pub fn debugPrint(storage: *Archetype) void {
std.debug.print("Archetype hash={} len={} capacity={} columns={}\n", .{ storage.hash, storage.len, storage.capacity, storage.columns.len });
for (storage.columns, 0..) |*column, i| {
std.debug.print("{}. '{s}'\n", .{ i, storage.component_names.string(column.name) });
}
}
pub const is_debug = builtin.mode == .Debug;
/// Returns a unique comptime usize integer representing the type T. Value will change across

120
src/module/entities.zig
View file

@ -77,11 +77,10 @@ pub fn Database(comptime modules: anytype) type {
return struct {
allocator: Allocator,
/// TODO!
/// TODO: entity ID recycling
counter: EntityID = 0,
/// A mapping of entity IDs (array indices) to where an entity's component values are actually
/// stored.
/// A mapping of entity IDs to where an entity's component values are actually stored.
entities: std.AutoHashMapUnmanaged(EntityID, Pointer) = .{},
// All archetypes are stored in a bucket. The number of buckets is configurable, and which
@ -196,7 +195,7 @@ pub fn Database(comptime modules: anytype) type {
const bucket_index = hash % entities.buckets.len;
if (entities.buckets[bucket_index]) |bucket| {
// Bucket already exists
const archetype = &entities.archetypes.items[bucket];
var archetype = &entities.archetypes.items[bucket];
if (archetype.next) |_| {
// Multiple archetypes in bucket (there were collisions)
while (archetype.next) |collision_index| {
@ -207,6 +206,7 @@ pub fn Database(comptime modules: anytype) type {
// column IDs are equal here too?
return .{ .found_existing = true, .hash = hash, .index = collision_index, .ptr = collision };
}
archetype = collision;
}
// New collision
@ -339,101 +339,13 @@ pub fn Database(comptime modules: anytype) type {
Archetype.typeId(@TypeOf(component)),
);
// TODO: DRY with setComponentDynamic, but verify this is functionally equivalent in all cases:
//
// return entities.setComponentDynamic(
// entity,
// name_id,
// std.mem.asBytes(&component),
// @alignOf(@TypeOf(component)),
// Archetype.typeId(@TypeOf(component)),
// );
const prev_archetype_idx = entities.entities.get(entity).?.archetype_index;
var prev_archetype = &entities.archetypes.items[prev_archetype_idx];
var archetype: ?*Archetype = if (prev_archetype.hasComponent(name_id)) prev_archetype else null;
var archetype_idx: u32 = if (archetype != null) prev_archetype_idx else 0;
if (archetype == null) {
// TODO: eliminate the need for allocation and sorting here, since this can occur
// if an archetype already exists (found_existing case below)
const columns = try entities.allocator.alloc(Archetype.Column, prev_archetype.columns.len + 1);
@memcpy(columns[0 .. columns.len - 1], prev_archetype.columns);
for (columns) |*column| {
column.values = undefined;
}
columns[columns.len - 1] = .{
.name = name_id,
.type_id = Archetype.typeId(@TypeOf(component)),
.size = @sizeOf(@TypeOf(component)),
.alignment = if (@sizeOf(@TypeOf(component)) == 0) 1 else @alignOf(@TypeOf(component)),
.values = undefined,
};
std.sort.pdq(Archetype.Column, columns, {}, byTypeId);
const archetype_entry = try entities.archetypeOrPut(columns);
if (!archetype_entry.found_existing) {
// Update prev_archetype pointer, as it would now be invalidated due to the allocation
prev_archetype = &entities.archetypes.items[prev_archetype_idx];
archetype_entry.ptr.* = .{
.len = 0,
.capacity = 0,
.columns = columns,
.component_names = entities.component_names,
.hash = archetype_entry.hash,
};
} else {
entities.allocator.free(columns);
}
archetype = archetype_entry.ptr;
archetype_idx = archetype_entry.index;
}
// Either new storage (if the entity moved between storage tables due to having a new
// component) or the prior storage (if the entity already had the component and it's value
// is merely being updated.)
var current_archetype_storage = archetype.?;
if (archetype_idx == prev_archetype_idx) {
// Update the value of the existing component of the entity.
const ptr = entities.entities.get(entity).?;
current_archetype_storage.set(ptr.row_index, name_id, component);
return;
}
// Copy to all component values for our entity from the old archetype storage (archetype)
// to the new one (current_archetype_storage).
const new_row = try current_archetype_storage.appendUndefined(entities.allocator);
const old_ptr = entities.entities.get(entity).?;
// Update the storage/columns for all of the existing components on the entity.
current_archetype_storage.set(new_row, entities.id_name, entity);
for (prev_archetype.columns) |column| {
if (column.name == entities.id_name) continue;
for (current_archetype_storage.columns) |corresponding| {
if (column.name == corresponding.name) {
const old_value_raw = prev_archetype.getDynamic(old_ptr.row_index, column.name, column.size, column.alignment, column.type_id).?;
current_archetype_storage.setDynamic(new_row, corresponding.name, old_value_raw, corresponding.alignment, corresponding.type_id);
break;
}
}
}
// Update the storage/column for the new component.
current_archetype_storage.set(new_row, name_id, component);
prev_archetype.remove(old_ptr.row_index);
if (prev_archetype.len > 0) {
const swapped_entity_id = prev_archetype.get(old_ptr.row_index, entities.id_name, EntityID).?;
try entities.entities.put(entities.allocator, swapped_entity_id, old_ptr);
}
try entities.entities.put(entities.allocator, entity, Pointer{
.archetype_index = archetype_idx,
.row_index = new_row,
});
return;
return entities.setComponentDynamic(
entity,
name_id,
std.mem.asBytes(&component),
if (@sizeOf(@TypeOf(component)) == 0) 1 else @alignOf(@TypeOf(component)),
Archetype.typeId(@TypeOf(component)),
);
}
fn setComponentDynamicDeferred(
@ -480,7 +392,7 @@ pub fn Database(comptime modules: anytype) type {
const prev_archetype_idx = entities.entities.get(entity).?.archetype_index;
var prev_archetype = &entities.archetypes.items[prev_archetype_idx];
var archetype: ?*Archetype = if (prev_archetype.hasComponent(name_id)) prev_archetype else null;
var archetype_idx: u32 = if (archetype != null) prev_archetype_idx else 0;
var archetype_idx: ?u32 = if (archetype != null) prev_archetype_idx else null;
if (archetype == null) {
// TODO: eliminate the need for allocation and sorting here, since this can occur
@ -522,8 +434,9 @@ pub fn Database(comptime modules: anytype) type {
// component) or the prior storage (if the entity already had the component and it's value
// is merely being updated.)
var current_archetype_storage = archetype.?;
const current_archetype_idx = archetype_idx.?;
if (archetype_idx == prev_archetype_idx) {
if (current_archetype_idx == prev_archetype_idx) {
// Update the value of the existing component of the entity.
const ptr = entities.entities.get(entity).?;
current_archetype_storage.setDynamic(ptr.row_index, name_id, component, alignment, type_id);
@ -551,14 +464,17 @@ pub fn Database(comptime modules: anytype) type {
// Update the storage/column for the new component.
current_archetype_storage.setDynamic(new_row, name_id, component, alignment, type_id);
// Swap remove our row out of the previous archetype
prev_archetype.remove(old_ptr.row_index);
if (prev_archetype.len > 0) {
// If a swap removal did occur, then at our old slot in the archetype represents
// that entity. Update its pointer to point to its new location.
const swapped_entity_id = prev_archetype.get(old_ptr.row_index, entities.id_name, EntityID).?;
try entities.entities.put(entities.allocator, swapped_entity_id, old_ptr);
}
try entities.entities.put(entities.allocator, entity, Pointer{
.archetype_index = archetype_idx,
.archetype_index = current_archetype_idx,
.row_index = new_row,
});
return;