AdaptiveByteBuf() — netty Function Reference

Source Code

buffer/src/main/java/io/netty/buffer/AdaptivePoolingAllocator.java lines 393–433

        public AdaptiveByteBuf allocate(int size, int maxCapacity, Thread currentThread, AdaptiveByteBuf buf) {
            boolean reallocate = buf != null;

            // Path for thread-local allocation.
            Magazine tlMag = threadLocalMagazine;
            if (tlMag != null) {
                if (buf == null) {
                    buf = tlMag.newBuffer();
                }
                boolean allocated = tlMag.tryAllocate(size, maxCapacity, buf, reallocate);
                assert allocated : "Allocation of threadLocalMagazine must always succeed";
                return buf;
            }

            // Path for concurrent allocation.
            long threadId = currentThread.getId();
            Magazine[] mags;
            int expansions = 0;
            do {
                mags = magazines;
                int mask = mags.length - 1;
                int index = (int) (threadId & mask);
                for (int i = 0, m = mags.length << 1; i < m; i++) {
                    Magazine mag = mags[index + i & mask];
                    if (buf == null) {
                        buf = mag.newBuffer();
                    }
                    if (mag.tryAllocate(size, maxCapacity, buf, reallocate)) {
                        // Was able to allocate.
                        return buf;
                    }
                }
                expansions++;
            } while (expansions <= EXPANSION_ATTEMPTS && tryExpandMagazines(mags.length));

            // The magazines failed us; contention too high and we don't want to spend more effort expanding the array.
            if (!reallocate && buf != null) {
                buf.release(); // Release the previously claimed buffer before we return.
            }
            return null;
        }