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Make ThreadSafeFixedBufferAllocator alias FixedBufferAllocator when --single-threaded

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Fixes #1910
This commit is contained in:
John Schmidt 2019-02-07 21:28:37 +01:00 committed by Andrew Kelley
parent f330eebe4b
commit be6d022257
1 changed files with 48 additions and 42 deletions
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90
std/heap.zig
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@ -321,51 +321,57 @@ pub const FixedBufferAllocator = struct {
fn free(allocator: *Allocator, bytes: []u8) void {}
};
/// lock free
pub const ThreadSafeFixedBufferAllocator = struct {
allocator: Allocator,
end_index: usize,
buffer: []u8,
pub const ThreadSafeFixedBufferAllocator = blk: {
if (builtin.single_threaded) {
break :blk FixedBufferAllocator;
} else {
/// lock free
break :blk struct {
allocator: Allocator,
end_index: usize,
buffer: []u8,
pub fn init(buffer: []u8) ThreadSafeFixedBufferAllocator {
return ThreadSafeFixedBufferAllocator{
.allocator = Allocator{
.allocFn = alloc,
.reallocFn = realloc,
.freeFn = free,
},
.buffer = buffer,
.end_index = 0,
pub fn init(buffer: []u8) ThreadSafeFixedBufferAllocator {
return ThreadSafeFixedBufferAllocator{
.allocator = Allocator{
.allocFn = alloc,
.reallocFn = realloc,
.freeFn = free,
},
.buffer = buffer,
.end_index = 0,
};
}
fn alloc(allocator: *Allocator, n: usize, alignment: u29) ![]u8 {
const self = @fieldParentPtr(ThreadSafeFixedBufferAllocator, "allocator", allocator);
var end_index = @atomicLoad(usize, &self.end_index, builtin.AtomicOrder.SeqCst);
while (true) {
const addr = @ptrToInt(self.buffer.ptr) + end_index;
const rem = @rem(addr, alignment);
const march_forward_bytes = if (rem == 0) 0 else (alignment - rem);
const adjusted_index = end_index + march_forward_bytes;
const new_end_index = adjusted_index + n;
if (new_end_index > self.buffer.len) {
return error.OutOfMemory;
}
end_index = @cmpxchgWeak(usize, &self.end_index, end_index, new_end_index, builtin.AtomicOrder.SeqCst, builtin.AtomicOrder.SeqCst) orelse return self.buffer[adjusted_index..new_end_index];
}
}
fn realloc(allocator: *Allocator, old_mem: []u8, new_size: usize, alignment: u29) ![]u8 {
if (new_size <= old_mem.len) {
return old_mem[0..new_size];
} else {
const result = try alloc(allocator, new_size, alignment);
mem.copy(u8, result, old_mem);
return result;
}
}
fn free(allocator: *Allocator, bytes: []u8) void {}
};
}
fn alloc(allocator: *Allocator, n: usize, alignment: u29) ![]u8 {
const self = @fieldParentPtr(ThreadSafeFixedBufferAllocator, "allocator", allocator);
var end_index = @atomicLoad(usize, &self.end_index, builtin.AtomicOrder.SeqCst);
while (true) {
const addr = @ptrToInt(self.buffer.ptr) + end_index;
const rem = @rem(addr, alignment);
const march_forward_bytes = if (rem == 0) 0 else (alignment - rem);
const adjusted_index = end_index + march_forward_bytes;
const new_end_index = adjusted_index + n;
if (new_end_index > self.buffer.len) {
return error.OutOfMemory;
}
end_index = @cmpxchgWeak(usize, &self.end_index, end_index, new_end_index, builtin.AtomicOrder.SeqCst, builtin.AtomicOrder.SeqCst) orelse return self.buffer[adjusted_index..new_end_index];
}
}
fn realloc(allocator: *Allocator, old_mem: []u8, new_size: usize, alignment: u29) ![]u8 {
if (new_size <= old_mem.len) {
return old_mem[0..new_size];
} else {
const result = try alloc(allocator, new_size, alignment);
mem.copy(u8, result, old_mem);
return result;
}
}
fn free(allocator: *Allocator, bytes: []u8) void {}
};
pub fn stackFallback(comptime size: usize, fallback_allocator: *Allocator) StackFallbackAllocator(size) {