Commit fe42313
authored
Remove dependency on sun.misc.Unsafe (prometheus#547)
This replaces `sun.misc.Unsafe` with
`java.util.concurrent.atomic.AtomicLongFieldUpdater` and
`AtomicIntegerFieldUpdater`. This is to enable compatibility with Jigsaw
modules where `sun.misc.Unsafe` is no longer available.
Closes prometheus#468
Signed-off-by: Andre Masella <andre@masella.name>1 parent ac5136b commit fe42313
1 file changed
Lines changed: 8 additions & 61 deletions
Lines changed: 8 additions & 61 deletions
| Original file line number | Diff line number | Diff line change | |
|---|---|---|---|
@@ -9,6 +9,8 @@ | |||
| 9 | 9 | package io.prometheus.client; | |
| 10 | 10 | ||
| 11 | 11 | import java.util.Random; | |
| 12 | + import java.util.concurrent.atomic.AtomicIntegerFieldUpdater; | ||
| 13 | + import java.util.concurrent.atomic.AtomicLongFieldUpdater; | ||
| 12 | 14 | ||
| 13 | 15 | /** | |
| 14 | 16 | * A package-local class holding common representation and mechanics | |
@@ -94,22 +96,10 @@ static final class Cell { | |||
| 94 | 96 | Cell(long x) { value = x; } | |
| 95 | 97 | ||
| 96 | 98 | final boolean cas(long cmp, long val) { | |
| 97 | - return UNSAFE.compareAndSwapLong(this, valueOffset, cmp, val); | ||
| 99 | + return CAS_VALUE.compareAndSet(this, cmp, val); | ||
| 98 | 100 | } | |
| 99 | 101 | ||
| 100 | - // Unsafe mechanics | ||
| 101 | - private static final sun.misc.Unsafe UNSAFE; | ||
| 102 | - private static final long valueOffset; | ||
| 103 | - static { | ||
| 104 | - try { | ||
| 105 | - UNSAFE = getUnsafe(); | ||
| 106 | - Class<?> ak = Cell.class; | ||
| 107 | - valueOffset = UNSAFE.objectFieldOffset | ||
| 108 | - (ak.getDeclaredField("value")); | ||
| 109 | - } catch (Exception e) { | ||
| 110 | - throw new Error(e); | ||
| 111 | - } | ||
| 112 | - } | ||
| 102 | + private static final AtomicLongFieldUpdater<Cell> CAS_VALUE = AtomicLongFieldUpdater.newUpdater(Cell.class, "value"); | ||
| 113 | 103 | ||
| 114 | 104 | } | |
| 115 | 105 | ||
@@ -155,14 +145,14 @@ final boolean cas(long cmp, long val) { | |||
| 155 | 145 | * CASes the base field. | |
| 156 | 146 | */ | |
| 157 | 147 | final boolean casBase(long cmp, long val) { | |
| 158 | - return UNSAFE.compareAndSwapLong(this, baseOffset, cmp, val); | ||
| 148 | + return CAS_BASE.compareAndSet(this, cmp, val); | ||
| 159 | 149 | } | |
| 160 | 150 | ||
| 161 | 151 | /** | |
| 162 | 152 | * CASes the busy field from 0 to 1 to acquire lock. | |
| 163 | 153 | */ | |
| 164 | 154 | final boolean casBusy() { | |
| 165 | - return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1); | ||
| 155 | + return CAS_BUSY.compareAndSet(this, 0, 1); | ||
| 166 | 156 | } | |
| 167 | 157 | ||
| 168 | 158 | /** | |
@@ -287,50 +277,7 @@ final void internalReset(long initialValue) { | |||
| 287 | 277 | } | |
| 288 | 278 | } | |
| 289 | 279 | ||
| 290 | - // Unsafe mechanics | ||
| 291 | - private static final sun.misc.Unsafe UNSAFE; | ||
| 292 | - private static final long baseOffset; | ||
| 293 | - private static final long busyOffset; | ||
| 294 | - static { | ||
| 295 | - try { | ||
| 296 | - UNSAFE = getUnsafe(); | ||
| 297 | - Class<?> sk = Striped64.class; | ||
| 298 | - baseOffset = UNSAFE.objectFieldOffset | ||
| 299 | - (sk.getDeclaredField("base")); | ||
| 300 | - busyOffset = UNSAFE.objectFieldOffset | ||
| 301 | - (sk.getDeclaredField("busy")); | ||
| 302 | - } catch (Exception e) { | ||
| 303 | - throw new Error(e); | ||
| 304 | - } | ||
| 305 | - } | ||
| 280 | + private static final AtomicLongFieldUpdater<Striped64> CAS_BASE = AtomicLongFieldUpdater.newUpdater(Striped64.class, "base"); | ||
| 281 | + private static final AtomicIntegerFieldUpdater<Striped64> CAS_BUSY = AtomicIntegerFieldUpdater.newUpdater(Striped64.class, "busy"); | ||
| 306 | 282 | ||
| 307 | - /** | ||
| 308 | - * Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. | ||
| 309 | - * Replace with a simple call to Unsafe.getUnsafe when integrating | ||
| 310 | - * into a jdk. | ||
| 311 | - * | ||
| 312 | - * @return a sun.misc.Unsafe | ||
| 313 | - */ | ||
| 314 | - private static sun.misc.Unsafe getUnsafe() { | ||
| 315 | - try { | ||
| 316 | - return sun.misc.Unsafe.getUnsafe(); | ||
| 317 | - } catch (SecurityException tryReflectionInstead) {} | ||
| 318 | - try { | ||
| 319 | - return java.security.AccessController.doPrivileged | ||
| 320 | - (new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() { | ||
| 321 | - public sun.misc.Unsafe run() throws Exception { | ||
| 322 | - Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class; | ||
| 323 | - for (java.lang.reflect.Field f : k.getDeclaredFields()) { | ||
| 324 | - f.setAccessible(true); | ||
| 325 | - Object x = f.get(null); | ||
| 326 | - if (k.isInstance(x)) | ||
| 327 | - return k.cast(x); | ||
| 328 | - } | ||
| 329 | - throw new NoSuchFieldError("the Unsafe"); | ||
| 330 | - }}); | ||
| 331 | - } catch (java.security.PrivilegedActionException e) { | ||
| 332 | - throw new RuntimeException("Could not initialize intrinsics", | ||
| 333 | - e.getCause()); | ||
| 334 | - } | ||
| 335 | - } | ||
| 336 | 283 | } | |
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