Merge pull request #25302 from ziglang/growCapacity

std: remove loop from growCapacity

lib/std/Io/Writer.zig

@@ -2667,7 +2667,7 @@ pub const Allocating = struct {
     pub fn ensureTotalCapacity(a: *Allocating, new_capacity: usize) Allocator.Error!void {
         // Protects growing unnecessarily since better_capacity will be larger.
         if (a.writer.buffer.len >= new_capacity) return;
-        const better_capacity = ArrayList(u8).growCapacity(a.writer.buffer.len, new_capacity);
+        const better_capacity = ArrayList(u8).growCapacity(new_capacity);
         return ensureTotalCapacityPrecise(a, better_capacity);
     }
 

lib/std/array_list.zig

@@ -172,7 +172,7 @@ pub fn AlignedManaged(comptime T: type, comptime alignment: ?mem.Alignment) type
             // a new buffer and doing our own copy. With a realloc() call,
             // the allocator implementation would pointlessly copy our
             // extra capacity.
-            const new_capacity = Aligned(T, alignment).growCapacity(self.capacity, new_len);
+            const new_capacity = Aligned(T, alignment).growCapacity(new_len);
             const old_memory = self.allocatedSlice();
             if (self.allocator.remap(old_memory, new_capacity)) |new_memory| {
                 self.items.ptr = new_memory.ptr;
@@ -408,7 +408,7 @@ pub fn AlignedManaged(comptime T: type, comptime alignment: ?mem.Alignment) type
             // Protects growing unnecessarily since better_capacity will be larger.
             if (self.capacity >= new_capacity) return;
 
-            const better_capacity = Aligned(T, alignment).growCapacity(self.capacity, new_capacity);
+            const better_capacity = Aligned(T, alignment).growCapacity(new_capacity);
             return self.ensureTotalCapacityPrecise(better_capacity);
         }
 
@@ -1160,7 +1160,7 @@ pub fn Aligned(comptime T: type, comptime alignment: ?mem.Alignment) type {
         /// Invalidates element pointers if additional memory is needed.
         pub fn ensureTotalCapacity(self: *Self, gpa: Allocator, new_capacity: usize) Allocator.Error!void {
             if (self.capacity >= new_capacity) return;
-            return self.ensureTotalCapacityPrecise(gpa, growCapacity(self.capacity, new_capacity));
+            return self.ensureTotalCapacityPrecise(gpa, growCapacity(new_capacity));
         }
 
         /// If the current capacity is less than `new_capacity`, this function will
@@ -1359,17 +1359,12 @@ pub fn Aligned(comptime T: type, comptime alignment: ?mem.Alignment) type {
             return self.getLast();
         }
 
-        const init_capacity = @as(comptime_int, @max(1, std.atomic.cache_line / @sizeOf(T)));
+        const init_capacity: comptime_int = @max(1, std.atomic.cache_line / @sizeOf(T));
 
         /// Called when memory growth is necessary. Returns a capacity larger than
         /// minimum that grows super-linearly.
-        pub fn growCapacity(current: usize, minimum: usize) usize {
+        pub fn growCapacity(minimum: usize) usize {
-            var new = current;
+            return minimum +| (minimum / 2 + init_capacity);
-            while (true) {
-                new +|= new / 2 + init_capacity;
-                if (new >= minimum)
-                    return new;
-            }
         }
     };
 }

lib/std/deque.zig

@@ -56,7 +56,7 @@ pub fn Deque(comptime T: type) type {
         /// Invalidates element pointers if additional memory is needed.
         pub fn ensureTotalCapacity(deque: *Self, gpa: Allocator, new_capacity: usize) Allocator.Error!void {
             if (deque.buffer.len >= new_capacity) return;
-            return deque.ensureTotalCapacityPrecise(gpa, growCapacity(deque.buffer.len, new_capacity));
+            return deque.ensureTotalCapacityPrecise(gpa, std.ArrayList(T).growCapacity(new_capacity));
         }
 
         /// If the current capacity is less than `new_capacity`, this function will
@@ -243,18 +243,6 @@ pub fn Deque(comptime T: type) type {
                 return index - head_len;
             }
         }
-
-        const init_capacity: comptime_int = @max(1, std.atomic.cache_line / @sizeOf(T));
-
-        /// Called when memory growth is necessary. Returns a capacity larger than
-        /// minimum that grows super-linearly.
-        fn growCapacity(current: usize, minimum: usize) usize {
-            var new = current;
-            while (true) {
-                new +|= new / 2 + init_capacity;
-                if (new >= minimum) return new;
-            }
-        }
     };
 }
 

lib/std/json/scanner_test.zig

@@ -431,33 +431,6 @@ test "skipValue" {
     try std.testing.expectError(error.SyntaxError, testSkipValue("[102, 111, 111}"));
 }
 
-fn testEnsureStackCapacity(do_ensure: bool) !void {
-    var fail_alloc = std.testing.FailingAllocator.init(std.testing.allocator, .{ .fail_index = 1 });
-    const failing_allocator = fail_alloc.allocator();
-
-    const nestings = 2049; // intentionally not a power of 2.
-    var input_string: std.ArrayListUnmanaged(u8) = .empty;
-    try input_string.appendNTimes(std.testing.allocator, '[', nestings);
-    try input_string.appendNTimes(std.testing.allocator, ']', nestings);
-    defer input_string.deinit(std.testing.allocator);
-
-    var scanner = Scanner.initCompleteInput(failing_allocator, input_string.items);
-    defer scanner.deinit();
-
-    if (do_ensure) {
-        try scanner.ensureTotalStackCapacity(nestings);
-    }
-
-    try scanner.skipValue();
-    try std.testing.expectEqual(Token.end_of_document, try scanner.next());
-}
-test "ensureTotalStackCapacity" {
-    // Once to demonstrate failure.
-    try std.testing.expectError(error.OutOfMemory, testEnsureStackCapacity(false));
-    // Then to demonstrate it works.
-    try testEnsureStackCapacity(true);
-}
-
 fn testDiagnosticsFromSource(expected_error: ?anyerror, line: u64, col: u64, byte_offset: u64, source: anytype) !void {
     var diagnostics = Diagnostics{};
     source.enableDiagnostics(&diagnostics);

lib/std/json/static_test.zig

@@ -914,7 +914,7 @@ test "parse at comptime" {
         uptime: u64,
     };
     const config = comptime x: {
-        var buf: [256]u8 = undefined;
+        var buf: [300]u8 = undefined;
         var fba = std.heap.FixedBufferAllocator.init(&buf);
         const res = parseFromSliceLeaky(Config, fba.allocator(), doc, .{});
         // Assert no error can occur since we are

lib/std/multi_array_list.zig

@@ -457,24 +457,19 @@ pub fn MultiArrayList(comptime T: type) type {
         /// Invalidates element pointers if additional memory is needed.
         pub fn ensureTotalCapacity(self: *Self, gpa: Allocator, new_capacity: usize) Allocator.Error!void {
             if (self.capacity >= new_capacity) return;
-            return self.setCapacity(gpa, growCapacity(self.capacity, new_capacity));
+            return self.setCapacity(gpa, growCapacity(new_capacity));
         }
 
-        const init_capacity = init: {
+        const init_capacity: comptime_int = init: {
-            var max = 1;
+            var max: comptime_int = 1;
-            for (fields) |field| max = @as(comptime_int, @max(max, @sizeOf(field.type)));
+            for (fields) |field| max = @max(max, @sizeOf(field.type));
-            break :init @as(comptime_int, @max(1, std.atomic.cache_line / max));
+            break :init @max(1, std.atomic.cache_line / max);
         };
 
-        /// Called when memory growth is necessary. Returns a capacity larger than
+        /// Given a lower bound of required memory capacity, returns a larger value
-        /// minimum that grows super-linearly.
+        /// with super-linear growth.
-        fn growCapacity(current: usize, minimum: usize) usize {
+        pub fn growCapacity(minimum: usize) usize {
-            var new = current;
+            return minimum +| (minimum / 2 + init_capacity);
-            while (true) {
-                new +|= new / 2 + init_capacity;
-                if (new >= minimum)
-                    return new;
-            }
         }
 
         /// Modify the array so that it can hold at least `additional_count` **more** items.