1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 package org.chromium.mojo.system; 6 7 import java.nio.ByteBuffer; 8 9 /** 10 * Interface for data pipes. A data pipe is a unidirectional communication channel for unframed 11 * data. Data is unframed, but must come as (multiples of) discrete elements, of the size given at 12 * creation time. 13 */ 14 public interface DataPipe { 15 16 /** 17 * Flags for the data pipe creation operation. 18 */ 19 public static class CreateFlags extends Flags<CreateFlags> { 20 private static final int FLAG_NONE = 0; 21 22 /** 23 * Immutable flag with not bit set. 24 */ 25 public static final CreateFlags NONE = CreateFlags.none().immutable(); 26 27 /** 28 * Dedicated constructor. 29 * 30 * @param flags initial value of the flags. 31 */ 32 protected CreateFlags(int flags) { 33 super(flags); 34 } 35 36 /** 37 * @return flags with no bit set. 38 */ 39 public static CreateFlags none() { 40 return new CreateFlags(FLAG_NONE); 41 } 42 43 } 44 45 /** 46 * Used to specify creation parameters for a data pipe to |Core.createDataPipe()|. 47 */ 48 public static class CreateOptions { 49 50 /** 51 * Used to specify different modes of operation, see |DataPipe.CreateFlags|. 52 */ 53 private CreateFlags mFlags = CreateFlags.none(); 54 /** 55 * The size of an element, in bytes. All transactions and buffers will consist of an 56 * integral number of elements. Must be nonzero. 57 */ 58 private int mElementNumBytes; 59 /** 60 * The capacity of the data pipe, in number of bytes; must be a multiple of 61 * |element_num_bytes|. The data pipe will always be able to queue AT LEAST this much data. 62 * Set to zero to opt for a system-dependent automatically-calculated capacity (which will 63 * always be at least one element). 64 */ 65 private int mCapacityNumBytes; 66 67 /** 68 * @return the flags 69 */ 70 public CreateFlags getFlags() { 71 return mFlags; 72 } 73 74 /** 75 * @return the elementNumBytes 76 */ 77 public int getElementNumBytes() { 78 return mElementNumBytes; 79 } 80 81 /** 82 * @param elementNumBytes the elementNumBytes to set 83 */ 84 public void setElementNumBytes(int elementNumBytes) { 85 mElementNumBytes = elementNumBytes; 86 } 87 88 /** 89 * @return the capacityNumBytes 90 */ 91 public int getCapacityNumBytes() { 92 return mCapacityNumBytes; 93 } 94 95 /** 96 * @param capacityNumBytes the capacityNumBytes to set 97 */ 98 public void setCapacityNumBytes(int capacityNumBytes) { 99 mCapacityNumBytes = capacityNumBytes; 100 } 101 102 } 103 104 /** 105 * Flags for the write operations on MessagePipeHandle . 106 */ 107 public static class WriteFlags extends Flags<WriteFlags> { 108 private static final int FLAG_NONE = 0; 109 private static final int FLAG_ALL_OR_NONE = 1 << 0; 110 111 /** 112 * Immutable flag with not bit set. 113 */ 114 public static final WriteFlags NONE = WriteFlags.none().immutable(); 115 116 /** 117 * Dedicated constructor. 118 * 119 * @param flags initial value of the flags. 120 */ 121 private WriteFlags(int flags) { 122 super(flags); 123 } 124 125 /** 126 * Change the all-or-none bit of those flags. If set, write either all the elements 127 * requested or none of them. 128 * 129 * @param allOrNone the new value of all-or-none bit. 130 * @return this. 131 */ 132 public WriteFlags setAllOrNone(boolean allOrNone) { 133 return setFlag(FLAG_ALL_OR_NONE, allOrNone); 134 } 135 136 /** 137 * @return a flag with no bit set. 138 */ 139 public static WriteFlags none() { 140 return new WriteFlags(FLAG_NONE); 141 } 142 } 143 144 /** 145 * Flags for the read operations on MessagePipeHandle. 146 */ 147 public static class ReadFlags extends Flags<ReadFlags> { 148 private static final int FLAG_NONE = 0; 149 private static final int FLAG_ALL_OR_NONE = 1 << 0; 150 private static final int FLAG_QUERY = 1 << 2; 151 private static final int FLAG_PEEK = 1 << 3; 152 153 /** 154 * Immutable flag with not bit set. 155 */ 156 public static final ReadFlags NONE = ReadFlags.none().immutable(); 157 158 /** 159 * Dedicated constructor. 160 * 161 * @param flags initial value of the flag. 162 */ 163 private ReadFlags(int flags) { 164 super(flags); 165 } 166 167 /** 168 * Change the all-or-none bit of this flag. If set, read (or discard) either the requested 169 * number of elements or none. 170 * 171 * @param allOrNone the new value of the all-or-none bit. 172 * @return this. 173 */ 174 public ReadFlags setAllOrNone(boolean allOrNone) { 175 return setFlag(FLAG_ALL_OR_NONE, allOrNone); 176 } 177 178 /** 179 * Change the query bit of this flag. If set query the number of elements available to read. 180 * Mutually exclusive with |discard| and |allOrNone| is ignored if this flag is set. 181 * 182 * @param query the new value of the query bit. 183 * @return this. 184 */ 185 public ReadFlags query(boolean query) { 186 return setFlag(FLAG_QUERY, query); 187 } 188 189 /** 190 * Change the peek bit of this flag. If set, read the requested number of elements, and 191 * leave those elements in the pipe. A later read will return the same data. 192 * Mutually exclusive with |discard| and |query|. 193 * 194 * @param peek the new value of the peek bit. 195 * @return this. 196 */ 197 public ReadFlags peek(boolean peek) { 198 return setFlag(FLAG_PEEK, peek); 199 } 200 201 /** 202 * @return a flag with no bit set. 203 */ 204 public static ReadFlags none() { 205 return new ReadFlags(FLAG_NONE); 206 } 207 208 } 209 210 /** 211 * Handle for the producer part of a data pipe. 212 */ 213 public static interface ProducerHandle extends Handle { 214 215 /** 216 * @see org.chromium.mojo.system.Handle#pass() 217 */ 218 @Override 219 public ProducerHandle pass(); 220 221 /** 222 * Writes the given data to the data pipe producer. |elements| points to data; the buffer 223 * must be a direct ByteBuffer and the limit should be a multiple of the data pipe's element 224 * size. If |allOrNone| is set in |flags|, either all the data will be written or none is. 225 * <p> 226 * On success, returns the amount of data that was actually written. 227 * <p> 228 * Note: If the data pipe has the "may discard" option flag (specified on creation), this 229 * will discard as much data as required to write the given data, starting with the earliest 230 * written data that has not been consumed. However, even with "may discard", if the buffer 231 * limit is greater than the data pipe's capacity (and |allOrNone| is not set), this will 232 * write the maximum amount possible (namely, the data pipe's capacity) and return that 233 * amount. It will *not* discard data from |elements|. 234 * 235 * @return number of written bytes. 236 */ 237 public ResultAnd<Integer> writeData(ByteBuffer elements, WriteFlags flags); 238 239 /** 240 * Begins a two-phase write to the data pipe producer . On success, returns a |ByteBuffer| 241 * to which the caller can write. If flags has |allOrNone| set, then the buffer capacity 242 * will be at least as large as |numBytes|, which must also be a multiple of the element 243 * size (if |allOrNone| is not set, |numBytes| is ignored and the caller must check the 244 * capacity of the buffer). 245 * <p> 246 * During a two-phase write, this handle is *not* writable. E.g., if another thread tries to 247 * write to it, it will throw a |MojoException| with code |MojoResult.BUSY|; that thread can 248 * then wait for this handle to become writable again. 249 * <p> 250 * Once the caller has finished writing data to the buffer, it should call |endWriteData()| 251 * to specify the amount written and to complete the two-phase write. 252 * <p> 253 * Note: If the data pipe has the "may discard" option flag (specified on creation) and 254 * |flags| has |allOrNone| set, this may discard some data. 255 * 256 * @return The buffer to write to. 257 */ 258 public ByteBuffer beginWriteData(int numBytes, WriteFlags flags); 259 260 /** 261 * Ends a two-phase write to the data pipe producer that was begun by a call to 262 * |beginWriteData()| on the same handle. |numBytesWritten| should indicate the amount of 263 * data actually written; it must be less than or equal to the capacity of the buffer 264 * returned by |beginWriteData()| and must be a multiple of the element size. The buffer 265 * returned from |beginWriteData()| must have been filled with exactly |numBytesWritten| 266 * bytes of data. 267 * <p> 268 * On failure, the two-phase write (if any) is ended (so the handle may become writable 269 * again, if there's space available) but no data written to the buffer is "put into" the 270 * data pipe. 271 */ 272 public void endWriteData(int numBytesWritten); 273 } 274 275 /** 276 * Handle for the consumer part of a data pipe. 277 */ 278 public static interface ConsumerHandle extends Handle { 279 /** 280 * @see org.chromium.mojo.system.Handle#pass() 281 */ 282 @Override 283 public ConsumerHandle pass(); 284 285 /** 286 * Discards data on the data pie consumer. This method discards up to |numBytes| (which 287 * again be a multiple of the element size) bytes of data, returning the amount actually 288 * discarded. if |flags| has |allOrNone|, it will either discard exactly |numBytes| bytes of 289 * data or none. In this case, |query| must not be set. 290 */ 291 public int discardData(int numBytes, ReadFlags flags); 292 293 /** 294 * Reads data from the data pipe consumer. May also be used to query the amount of data 295 * available. If |flags| has not |query| set, this tries to read up to |elements| capacity 296 * (which must be a multiple of the data pipe's element size) bytes of data to |elements| 297 * and returns the amount actually read. |elements| must be a direct ByteBuffer. If flags 298 * has |allOrNone| set, it will either read exactly |elements| capacity bytes of data or 299 * none. 300 * <p> 301 * If flags has |query| set, it queries the amount of data available, returning the number 302 * of bytes available. In this case |allOrNone| is ignored, as are |elements|. 303 */ 304 public ResultAnd<Integer> readData(ByteBuffer elements, ReadFlags flags); 305 306 /** 307 * Begins a two-phase read from the data pipe consumer. On success, returns a |ByteBuffer| 308 * from which the caller can read up to its limit bytes of data. If flags has |allOrNone| 309 * set, then the limit will be at least as large as |numBytes|, which must also be a 310 * multiple of the element size (if |allOrNone| is not set, |numBytes| is ignored). |flags| 311 * must not have |query| set. 312 * <p> 313 * During a two-phase read, this handle is *not* readable. E.g., if another thread tries to 314 * read from it, it will throw a |MojoException| with code |MojoResult.BUSY|; that thread 315 * can then wait for this handle to become readable again. 316 * <p> 317 * Once the caller has finished reading data from the buffer, it should call |endReadData()| 318 * to specify the amount read and to complete the two-phase read. 319 */ 320 public ByteBuffer beginReadData(int numBytes, ReadFlags flags); 321 322 /** 323 * Ends a two-phase read from the data pipe consumer that was begun by a call to 324 * |beginReadData()| on the same handle. |numBytesRead| should indicate the amount of data 325 * actually read; it must be less than or equal to the limit of the buffer returned by 326 * |beginReadData()| and must be a multiple of the element size. 327 * <p> 328 * On failure, the two-phase read (if any) is ended (so the handle may become readable 329 * again) but no data is "removed" from the data pipe. 330 */ 331 public void endReadData(int numBytesRead); 332 } 333 334 } 335
