move linker input file parsing to the compilation pipeline

src/ThreadSafeQueue.zig

@@ -0,0 +1,63 @@
+const std = @import("std");
+const assert = std.debug.assert;
+const Allocator = std.mem.Allocator;
+
+pub fn ThreadSafeQueue(comptime T: type) type {
+    return struct {
+        worker_owned: std.ArrayListUnmanaged(T),
+        /// Protected by `mutex`.
+        shared: std.ArrayListUnmanaged(T),
+        mutex: std.Thread.Mutex,
+        state: State,
+
+        const Self = @This();
+
+        pub const State = enum { wait, run };
+
+        pub const empty: Self = .{
+            .worker_owned = .empty,
+            .shared = .empty,
+            .mutex = .{},
+            .state = .wait,
+        };
+
+        pub fn deinit(self: *Self, gpa: Allocator) void {
+            self.worker_owned.deinit(gpa);
+            self.shared.deinit(gpa);
+            self.* = undefined;
+        }
+
+        /// Must be called from the worker thread.
+        pub fn check(self: *Self) ?[]T {
+            assert(self.worker_owned.items.len == 0);
+            {
+                self.mutex.lock();
+                defer self.mutex.unlock();
+                assert(self.state == .run);
+                if (self.shared.items.len == 0) {
+                    self.state = .wait;
+                    return null;
+                }
+                std.mem.swap(std.ArrayListUnmanaged(T), &self.worker_owned, &self.shared);
+            }
+            const result = self.worker_owned.items;
+            self.worker_owned.clearRetainingCapacity();
+            return result;
+        }
+
+        /// Adds items to the queue, returning true if and only if the worker
+        /// thread is waiting. Thread-safe.
+        /// Not safe to call from the worker thread.
+        pub fn enqueue(self: *Self, gpa: Allocator, items: []const T) error{OutOfMemory}!bool {
+            self.mutex.lock();
+            defer self.mutex.unlock();
+            try self.shared.appendSlice(gpa, items);
+            const was_waiting = switch (self.state) {
+                .run => false,
+                .wait => true,
+            };
+            self.state = .run;
+            return was_waiting;
+        }
+    };
+}