1 /* 2 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package sun.java2d.pipe; 27 28 import java.util.HashSet; 29 import java.util.Set; 30 import sun.awt.SunToolkit; 31 32 /** 33 * The RenderQueue class encapsulates a RenderBuffer on which rendering 34 * operations are enqueued. Note that the RenderQueue lock must be acquired 35 * before performing any operations on the queue (e.g. enqueuing an operation 36 * or flushing the queue). A sample usage scenario follows: 37 * 38 * public void drawSomething(...) { 39 * rq.lock(); 40 * try { 41 * ctx.validate(...); 42 * rq.ensureCapacity(4); 43 * rq.getBuffer().putInt(DRAW_SOMETHING); 44 * ... 45 * } finally { 46 * rq.unlock(); 47 * } 48 * } 49 * 50 * If you are enqueuing an operation that involves 8-byte parameters (i.e. 51 * long or double values), it is imperative that you ensure proper 52 * alignment of the underlying RenderBuffer. This can be accomplished 53 * simply by providing an offset to the first 8-byte parameter in your 54 * operation to the ensureCapacityAndAlignment() method. For example: 55 * 56 * public void drawStuff(...) { 57 * rq.lock(); 58 * try { 59 * RenderBuffer buf = rq.getBuffer(); 60 * ctx.validate(...); 61 * // 28 total bytes in the operation, 12 bytes to the first long 62 * rq.ensureCapacityAndAlignment(28, 12); 63 * buf.putInt(DRAW_STUFF); 64 * buf.putInt(x).putInt(y); 65 * buf.putLong(addr1); 66 * buf.putLong(addr2); 67 * } finally { 68 * rq.unlock(); 69 * } 70 * } 71 */ 72 public abstract class RenderQueue { 73 74 /** The size of the underlying buffer, in bytes. */ 75 private static final int BUFFER_SIZE = 32000; 76 77 /** The underlying buffer for this queue. */ 78 protected RenderBuffer buf; 79 80 /** 81 * A Set containing hard references to Objects that must stay alive until 82 * the queue has been completely flushed. 83 */ 84 protected Set<Object> refSet; 85 RenderQueue()86 protected RenderQueue() { 87 refSet = new HashSet<>(); 88 buf = RenderBuffer.allocate(BUFFER_SIZE); 89 } 90 91 /** 92 * Locks the queue for read/write access. 93 */ lock()94 public final void lock() { 95 /* 96 * Implementation note: In theory we should have two separate locks: 97 * one lock to synchronize access to the RenderQueue, and then a 98 * separate lock (the AWT lock) that only needs to be acquired when 99 * we are about to flush the queue (using native windowing system 100 * operations). In practice it has been difficult to enforce the 101 * correct lock ordering; sometimes AWT will have already acquired 102 * the AWT lock before grabbing the RQ lock (see 6253009), while the 103 * expected order should be RQ lock and then AWT lock. Due to this 104 * issue, using two separate locks is prone to deadlocks. Therefore, 105 * to solve this issue we have decided to eliminate the separate RQ 106 * lock and instead just acquire the AWT lock here. (Someday it might 107 * be nice to go back to the old two-lock system, but that would 108 * require potentially risky changes to AWT to ensure that it never 109 * acquires the AWT lock before calling into 2D code that wants to 110 * acquire the RQ lock.) 111 */ 112 SunToolkit.awtLock(); 113 } 114 115 /** 116 * Attempts to lock the queue. If successful, this method returns true, 117 * indicating that the caller is responsible for calling 118 * {@code unlock}; otherwise this method returns false. 119 */ tryLock()120 public final boolean tryLock() { 121 return SunToolkit.awtTryLock(); 122 } 123 124 /** 125 * Unlocks the queue. 126 */ unlock()127 public final void unlock() { 128 SunToolkit.awtUnlock(); 129 } 130 131 /** 132 * Adds the given Object to the set of hard references, which will 133 * prevent that Object from being disposed until the queue has been 134 * flushed completely. This is useful in cases where some enqueued 135 * data could become invalid if the reference Object were garbage 136 * collected before the queue could be processed. (For example, keeping 137 * a hard reference to a FontStrike will prevent any enqueued glyph 138 * images associated with that strike from becoming invalid before the 139 * queue is flushed.) The reference set will be cleared immediately 140 * after the queue is flushed each time. 141 */ addReference(Object ref)142 public final void addReference(Object ref) { 143 refSet.add(ref); 144 } 145 146 /** 147 * Returns the encapsulated RenderBuffer object. 148 */ getBuffer()149 public final RenderBuffer getBuffer() { 150 return buf; 151 } 152 153 /** 154 * Ensures that there will be enough room on the underlying buffer 155 * for the following operation. If the operation will not fit given 156 * the remaining space, the buffer will be flushed immediately, leaving 157 * an empty buffer for the impending operation. 158 * 159 * @param opsize size (in bytes) of the following operation 160 */ ensureCapacity(int opsize)161 public final void ensureCapacity(int opsize) { 162 if (buf.remaining() < opsize) { 163 flushNow(); 164 } 165 } 166 167 /** 168 * Convenience method that is equivalent to calling ensureCapacity() 169 * followed by ensureAlignment(). The ensureCapacity() call allows for an 170 * extra 4 bytes of space in case the ensureAlignment() method needs to 171 * insert a NOOP token on the buffer. 172 * 173 * @param opsize size (in bytes) of the following operation 174 * @param first8ByteValueOffset offset (in bytes) from the current 175 * position to the first 8-byte value used in the following operation 176 */ ensureCapacityAndAlignment(int opsize, int first8ByteValueOffset)177 public final void ensureCapacityAndAlignment(int opsize, 178 int first8ByteValueOffset) 179 { 180 ensureCapacity(opsize + 4); 181 ensureAlignment(first8ByteValueOffset); 182 } 183 184 /** 185 * Inserts a 4-byte NOOP token when necessary to ensure that all 8-byte 186 * parameters for the following operation are added to the underlying 187 * buffer with an 8-byte memory alignment. 188 * 189 * @param first8ByteValueOffset offset (in bytes) from the current 190 * position to the first 8-byte value used in the following operation 191 */ ensureAlignment(int first8ByteValueOffset)192 public final void ensureAlignment(int first8ByteValueOffset) { 193 int first8ByteValuePosition = buf.position() + first8ByteValueOffset; 194 if ((first8ByteValuePosition & 7) != 0) { 195 buf.putInt(BufferedOpCodes.NOOP); 196 } 197 } 198 199 /** 200 * Immediately processes each operation currently pending on the buffer. 201 * This method will block until the entire buffer has been flushed. The 202 * queue lock must be acquired before calling this method. 203 */ flushNow()204 public abstract void flushNow(); 205 206 /** 207 * Immediately processes each operation currently pending on the buffer, 208 * and then invokes the provided task. This method will block until the 209 * entire buffer has been flushed and the provided task has been executed. 210 * The queue lock must be acquired before calling this method. 211 */ flushAndInvokeNow(Runnable task)212 public abstract void flushAndInvokeNow(Runnable task); 213 214 /** 215 * Updates the current position of the underlying buffer, and then 216 * flushes the queue immediately. This method is useful when native code 217 * has added data to the queue and needs to flush immediately. 218 */ flushNow(int position)219 public void flushNow(int position) { 220 buf.position(position); 221 flushNow(); 222 } 223 } 224