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cd6cdd0a75
The high level Allocator interface API functions will now do a `@returnAddress()` so that stack traces captured by allocator implementations have a return address that does not include the Allocator overhead functions. This makes `4` a more reasonable default for how many stack frames to capture.
90 lines
3.0 KiB
Zig
90 lines
3.0 KiB
Zig
const std = @import("../std.zig");
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const mem = std.mem;
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/// Allocator that fails after N allocations, useful for making sure out of
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/// memory conditions are handled correctly.
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///
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/// To use this, first initialize it and get an allocator with
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///
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/// `const failing_allocator = &FailingAllocator.init(<allocator>,
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/// <fail_index>).allocator;`
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///
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/// Then use `failing_allocator` anywhere you would have used a
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/// different allocator.
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pub const FailingAllocator = struct {
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allocator: mem.Allocator,
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index: usize,
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fail_index: usize,
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internal_allocator: *mem.Allocator,
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allocated_bytes: usize,
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freed_bytes: usize,
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allocations: usize,
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deallocations: usize,
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/// `fail_index` is the number of successful allocations you can
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/// expect from this allocator. The next allocation will fail.
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/// For example, if this is called with `fail_index` equal to 2,
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/// the following test will pass:
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///
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/// var a = try failing_alloc.create(i32);
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/// var b = try failing_alloc.create(i32);
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/// testing.expectError(error.OutOfMemory, failing_alloc.create(i32));
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pub fn init(allocator: *mem.Allocator, fail_index: usize) FailingAllocator {
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return FailingAllocator{
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.internal_allocator = allocator,
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.fail_index = fail_index,
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.index = 0,
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.allocated_bytes = 0,
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.freed_bytes = 0,
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.allocations = 0,
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.deallocations = 0,
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.allocator = mem.Allocator{
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.allocFn = alloc,
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.resizeFn = resize,
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},
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};
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}
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fn alloc(
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allocator: *std.mem.Allocator,
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len: usize,
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ptr_align: u29,
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len_align: u29,
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return_address: usize,
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) error{OutOfMemory}![]u8 {
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const self = @fieldParentPtr(FailingAllocator, "allocator", allocator);
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if (self.index == self.fail_index) {
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return error.OutOfMemory;
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}
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const result = try self.internal_allocator.allocFn(self.internal_allocator, len, ptr_align, len_align, return_address);
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self.allocated_bytes += result.len;
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self.allocations += 1;
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self.index += 1;
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return result;
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}
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fn resize(
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allocator: *std.mem.Allocator,
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old_mem: []u8,
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old_align: u29,
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new_len: usize,
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len_align: u29,
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ra: usize,
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) error{OutOfMemory}!usize {
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const self = @fieldParentPtr(FailingAllocator, "allocator", allocator);
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const r = self.internal_allocator.resizeFn(self.internal_allocator, old_mem, old_align, new_len, len_align, ra) catch |e| {
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std.debug.assert(new_len > old_mem.len);
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return e;
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};
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if (new_len == 0) {
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self.deallocations += 1;
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self.freed_bytes += old_mem.len;
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} else if (r < old_mem.len) {
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self.freed_bytes += old_mem.len - r;
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} else {
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self.allocated_bytes += r - old_mem.len;
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}
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return r;
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}
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};
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