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Add LoggingAllocator prototype #2338

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Jun 27, 2019
+47 −0
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Add LoggingAllocator prototype #2338

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47 changes: 47 additions & 0 deletions std/heap.zig
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Original file line number Diff line number Diff line change
@@ -565,6 +565,53 @@ pub fn StackFallbackAllocator(comptime size: usize) type {
};
}

pub const NoErrorOutStream = std.io.OutStream(error{});
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How does one acquire a NoErrorOutStream? If I were to for example use (try std.io.getStdErr()).outStream() this outstream has errors.

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I've used this before....:

diff --git a/std/debug.zig b/std/debug.zig
index c5741f390..6425a7526 100644
--- a/std/debug.zig
+++ b/std/debug.zig
@@ -2339,7 +2339,15 @@ fn readILeb128(in_stream: var) !i64 {
 }
 
 /// This should only be used in temporary test programs.
-pub const global_allocator = &global_fixed_allocator.allocator;
+var NoErrorStdErrStream = std.heap.NoErrorOutStream {
+    .writeFn = struct {
+        pub fn writeFn(out_stream: *std.heap.NoErrorOutStream, bytes: []const u8) error{}!void {
+            const stderr = io.getStdErr() catch return;
+            stderr.write(bytes) catch return;
+        }
+    }.writeFn,
+};
+pub const global_allocator = &std.heap.LoggingAllocator.init(&global_fixed_allocator.allocator, &NoErrorStdErrStream).allocator;

pub const LoggingAllocator = struct {
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doc comments please. when should someone use this? what are the semantics?

allocator: Allocator,
parentAllocator: *Allocator,
outStream: *NoErrorOutStream,

const Self = @This();

pub fn init(parentAllocator: *Allocator, outStream: *NoErrorOutStream) Self {
return Self{
.allocator = Allocator{
.reallocFn = realloc,
.shrinkFn = shrink,
},
.parentAllocator = parentAllocator,
.outStream = outStream,
};
}

fn realloc(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) ![]u8 {
const self = @fieldParentPtr(Self, "allocator", allocator);
if (old_mem.len == 0) {
self.outStream.print("allocation of {} ", new_size) catch unreachable;
} else {
self.outStream.print("resize from {} to {} ", old_mem.len, new_size) catch unreachable;
}
const result = self.parentAllocator.reallocFn(self.parentAllocator, old_mem, old_align, new_size, new_align);
if (result) |buff| {
self.outStream.print("success!\n") catch unreachable;
} else |err| {
self.outStream.print("failure!\n") catch unreachable;
}
return result;
}

fn shrink(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 {
const self = @fieldParentPtr(Self, "allocator", allocator);
const result = self.parentAllocator.shrinkFn(self.parentAllocator, old_mem, old_align, new_size, new_align);
if (new_size == 0) {
self.outStream.print("free of {} bytes success!\n", old_mem.len) catch unreachable;
} else {
self.outStream.print("shrink from {} bytes to {} bytes success!\n", old_mem.len, new_size) catch unreachable;
}
return result;
}
};

test "c_allocator" {
if (builtin.link_libc) {
var slice = try c_allocator.alloc(u8, 50);