Kym Object Allocation Fix #13

Merged
kayomn merged 3 commits from kym-object-alloc-fix into main 2023-06-03 22:07:19 +02:00
5 changed files with 171 additions and 37 deletions

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@ -79,8 +79,8 @@ pub fn Stack(comptime Value: type) type {
/// internal buffer by `growth_amount`, leaving `self` in the same state that it was in prior to starting the
/// grow.
///
/// Growing ahead of pushing operations is useful when the upper bound of pushes is well-understood, as it can
/// reduce the number of allocations required per push.
/// Growing ahead of multiple push operations is useful when the upper bound of pushes is well-understood, as it
/// can reduce the number of allocations required per push.
///
/// *Note* if the `capacity` field of `self` is a non-zero value, `allocator` must reference the same allocation
/// strategy as the one originally used to allocate the current internal buffer.

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@ -2,44 +2,167 @@ const debug = @import("./debug.zig");
const io = @import("./io.zig");
// TODO: Finish implementing.
const math = @import("./math.zig");
pub fn Map(comptime Index: type, comptime Element: type) type {
const std = @import("std");
///
/// Addressable mapping of integers described by `index_int` to values of type `Value`.
kayomn marked this conversation as resolved Outdated

Overly wordy comment

Overly wordy comment
///
/// Slab maps are similar to slot maps in that they have O(1) insertion and removal, however, use a flat table layout
/// instead of parallel arrays. This reduces memory usage in some cases and can be useful for data that does not need to
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Comment could do with clarification.

Comment could do with clarification.
/// be quickly iterated over, as values ordering is not guaranteed.
///
/// *Note* `index_int` values may be as big or as small as desired per the use-case of the consumer, however, integers
/// smaller than `usize` may result in the map reporting it is out of memory due to exhausting the addressable space
/// provided by the integer.
///
pub fn Map(comptime index_int: std.builtin.Type.Int, comptime Value: type) type {
return struct {
free_index: Index = 0,
entries: []Entry = &.{},
count: Index = 0,
table: []Entry = &.{},
///
/// Table entry which may either store an inserted value or an index to the next free entry in the table.
///
const Entry = union (enum) {
free_index: usize,
element: Element,
free_index: Index,
value: Value,
};
///
/// Used for indexing into the slab map.
///
const Index = math.Int(index_int);
///
/// Slab map type.
kayomn marked this conversation as resolved Outdated

Slab map type.

Slab *map* type.
///
const Self = @This();
pub fn fetch(self: *Self, index: Index) *Element {
const entry = &self.entries[index];
///
/// Overwrites the value referenced by `index` in `self`.
///
pub fn assign(self: *Self, index: Index, value: Value) void {
const entry = &self.table[index];
debug.assert(entry.* == .element);
debug.assert(entry.* == .value);
return &entry.element;
entry.value = value;
}
///
/// Fetches the value referenced by `index` in `self`, returning it.
///
pub fn fetch(self: *Self, index: Index) Value {
const entry = &self.table[index];
debug.assert(entry.* == .value);
return entry.value;
}
///
/// Deinitializes `self` and sets it to an invalid state, freeing all memory allocated by `allocator`.
///
/// *Note* if the `table` field of `self` is an allocated slice, `allocator` must reference the same allocation
/// strategy as the one originally used to allocate the current table.
///
pub fn deinit(self: *Self, allocator: io.Allocator) void {
io.deallocate(allocator, self.entries);
if (self.table.len == 0) {
return;
}
io.deallocate(allocator, self.table);
self.table = &.{};
self.count = 0;
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Review

free_index should be reset in here as well, otherwise re-uses of the data structure in future will have a corrupt initial state.

`free_index` should be reset in here as well, otherwise re-uses of the data structure in future will have a corrupt initial state.
self.free_index = 0;
}
pub fn insert(self: *Self, allocator: io.Allocator, value: Element) io.AllocationError!Index {
_ = self;
_ = allocator;
_ = value;
///
/// Attempts to grow the internal buffer of `self` by `growth_amount` using `allocator`.
///
/// The function returns [io.AllocatorError] if `allocator` could not commit the memory required to grow the
/// table by `growth_amount`, leaving `self` in the same state that it was in prior to starting the grow.
///
/// Growing ahead of multiple insertion operations is useful when the upper bound of insertions is well-
/// understood, as it can reduce the number of allocations required per insertion.
///
/// *Note* if the `table` field of `self` is an allocated slice, `allocator` must reference the same allocation
/// strategy as the one originally used to allocate the current table.
///
pub fn grow(self: *Self, allocator: io.Allocator, growth_amount: usize) io.AllocationError!void {
const grown_capacity = self.table.len + growth_amount;
const entries = try io.allocate_many(Entry, grown_capacity, allocator);
return 0;
errdefer io.deallocate(allocator, entries);
if (self.table.len != 0) {
for (0 .. self.table.len) |index| {
entries[index] = self.table[index];
}
for (self.table.len .. entries.len) |index| {
entries[index] = .{.free_index = 0};
}
io.deallocate(allocator, self.table);
}
self.table = entries;
}
///
/// Attempts to insert `value` into `self` as a new entry using `allocator` as the allocation strategy,
/// returning an index value representing a reference to the inserted value that may be queried through `self`
/// after.
///
/// The function returns [io.AllocationError] if `allocator` could not commit the memory required to grow the
/// internal buffer of `self` when necessary.
///
/// *Note* if the `table` field of `self` is an allocated slice, `allocator` must reference the same allocation
/// strategy as the one originally used to allocate the current table.
///
pub fn insert(self: *Self, allocator: io.Allocator, value: Value) io.AllocationError!Index {
if (self.count == self.table.len) {
try self.grow(allocator, math.max(1, self.count));
}
if (self.free_index == self.count) {
const entry_index = self.count;
const entry = &self.table[entry_index];
entry.* = .{.value = value};
self.count += 1;
self.free_index += 1;
return entry_index;
}
const entry_index = self.free_index;
const entry = &self.table[self.free_index];
debug.assert(entry.* == .free_index);
self.free_index = entry.free_index;
entry.* = .{.value = value};
return entry_index;
}
///
/// Removes the value referenced by `index` from `self`.
///
pub fn remove(self: *Self, index: Index) void {
const entry = &self.entries[index];
const entry = &self.table[index];
debug.assert(entry.* == .element);
debug.assert(entry.* == .value);
entry.* = .{.free_index = self.free_index};
self.free_index = index;
}
};
}

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@ -154,6 +154,10 @@ pub fn Hashed(comptime Key: type, comptime Value: type, comptime keyer: Keyer(Ke
/// `self`.
///
pub fn deinit(self: *Self, allocator: io.Allocator) void {
if (self.table.len == 0) {
return;
}
io.deallocate(allocator, self.table);
self.table = &.{};
@ -196,20 +200,18 @@ pub fn Hashed(comptime Key: type, comptime Value: type, comptime keyer: Keyer(Ke
return null;
}
{
const hash_max = math.min(math.max_int(hash_info), self.table.len);
var hashed_key = math.wrap(keyer.hasher(key), math.min_int(hash_info), hash_max);
var iterations = @as(usize, 0);
const hash_max = math.min(math.max_int(hash_info), self.table.len);
var hashed_key = math.wrap(keyer.hasher(key), math.min_int(hash_info), hash_max);
var iterations = @as(usize, 0);
while (iterations < self.count) : (iterations += 1) {
const entry = &(self.table[hashed_key] orelse return null);
while (iterations < self.count) : (iterations += 1) {
const entry = &(self.table[hashed_key] orelse return null);
if (keyer.comparer(entry.key, key) == 0) {
return entry.value;
}
hashed_key = (hashed_key +% 1) % hash_max;
if (keyer.comparer(entry.key, key) == 0) {
return entry.value;
}
hashed_key = (hashed_key +% 1) % hash_max;
}
return null;

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@ -143,7 +143,7 @@ pub const ObjectInfo = struct {
}
};
const ObjectSlab = coral.slab.Map(u32, Object);
const ObjectSlab = coral.slab.Map(@typeInfo(u32).Int, Object);
pub const Reporter = coral.io.Functor(void, []const u8);
@ -192,8 +192,12 @@ pub fn deinit(self: *Self) void {
pub fn discard(self: *Self, val: types.Val) void {
switch (val) {
.object => |object| {
if (!self.heap.fetch(object).release(self)) {
var data = self.heap.fetch(object);
if (data.release(self)) {
self.heap.remove(object);
} else {
self.heap.assign(object, data);
}
},
@ -267,12 +271,19 @@ pub fn get_field(self: *Self, indexable: types.Ref, field: types.Ref) !types.Val
try self.check(indexable == .object, "invalid type conversion: object");
try self.check(field == .object, "invalid type conversion: object");
const value = self.heap.fetch(indexable.object).state.fields.lookup(self.heap.fetch(field.object)) orelse {
return .nil;
const value = get_value: {
var field_data = self.heap.fetch(field.object);
break: get_value self.heap.fetch(indexable.object).state.fields.lookup(&field_data) orelse {
return .nil;
};
};
if (value == .object) {
self.heap.fetch(value.object).acquire();
var value_data = self.heap.fetch(value.object);
value_data.acquire();
self.heap.assign(value.object, value_data);
}
return value;

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@ -96,8 +96,6 @@ pub const Tokenizer = struct {
defer self.source = self.source[cursor ..];
defer @import("std").debug.print("{s}\n", .{self.current_token.text()});
while (cursor < self.source.len) {
switch (self.source[cursor]) {
'#' => {