1 files changed, 77 insertions, 0 deletions
diff --git a/src/galloc.zig b/src/galloc.zig
new file mode 100644
index 0000000..7cb4480
--- /dev/null
+++ b/src/galloc.zig
@@ -0,0 +1,77 @@
+const std = @import("std");
+const testing = std.testing;
+
+pub const GitAllocator = struct {
+    mutex: std.Thread.Mutex,
+    alloc: std.mem.Allocator,
+    allocs: std.AutoArrayHashMap(*anyopaque, []u8) = undefined,
+
+    pub fn init(alloc: std.mem.Allocator) GitAllocator {
+        return GitAllocator{
+            .alloc = alloc,
+            .allocs = std.AutoArrayHashMap(*anyopaque, []u8).init(alloc),
+            .mutex = std.Thread.Mutex{},
+        };
+    }
+
+    fn nalloc(self: *GitAllocator, size: usize) ?*anyopaque {
+        const frame = self.alloc.alloc(u8, size) catch return null;
+        self.allocs.put(frame.ptr, frame) catch return null;
+        return frame.ptr;
+    }
+
+    pub fn malloc(self: *GitAllocator, size: usize) ?*anyopaque {
+        self.mutex.lock();
+        defer self.mutex.unlock();
+        return self.nalloc(size);
+    }
+
+    pub fn realloc(self: *GitAllocator, nptr: ?*anyopaque, size: usize) ?*anyopaque {
+        self.mutex.lock();
+        defer self.mutex.unlock();
+
+        const ptr = nptr orelse return self.nalloc(size);
+
+        const frame = self.allocs.get(ptr) orelse return null;
+        if (!self.allocs.swapRemove(ptr)) {
+            @panic("failed to remove");
+        }
+
+        const new_frame = self.alloc.realloc(frame, size) catch return null;
+
+        self.allocs.put(new_frame.ptr, new_frame) catch return null;
+        return new_frame.ptr;
+    }
+
+    pub fn free(self: *GitAllocator, nptr: ?*anyopaque) void {
+        self.mutex.lock();
+        defer self.mutex.unlock();
+
+        const ptr = nptr orelse return;
+
+        const frame = self.allocs.get(ptr) orelse return;
+
+        defer self.alloc.free(frame);
+        if (!self.allocs.swapRemove(ptr)) {
+            @panic("failed to remove");
+        }
+    }
+
+    pub fn deinit(self: *GitAllocator) void {
+        self.allocs.deinit();
+    }
+};
+
+test "test git allocator" {
+    var gitAlloc = GitAllocator.init(testing.allocator);
+    defer gitAlloc.deinit();
+
+    var ptr = gitAlloc.malloc(2_000);
+
+    try testing.expect(ptr != null);
+
+    ptr = gitAlloc.realloc(ptr, 4_000);
+    ptr = gitAlloc.realloc(ptr, 1_000);
+
+    gitAlloc.free(ptr);
+}