DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Implementation

Untracked file

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef jsgc_h___
#define jsgc_h___
/*
 * JS Garbage Collector.
 */
#include "jsprvtd.h"
#include "jspubtd.h"
#include "jsdhash.h"
#include "jsbit.h"
#include "jsutil.h"

JS_BEGIN_EXTERN_C

JS_STATIC_ASSERT(JSTRACE_STRING == 2);

#define JSTRACE_NAMESPACE   3
#define JSTRACE_QNAME       4
#define JSTRACE_XML         5

/*
 * One past the maximum trace kind.
 */
#define JSTRACE_LIMIT       6

/*
 * We use the trace kinds as the types for all GC things except external
 * strings.
 */
#define GCX_OBJECT              JSTRACE_OBJECT      /* JSObject */
#define GCX_DOUBLE              JSTRACE_DOUBLE      /* jsdouble */
#define GCX_STRING              JSTRACE_STRING      /* JSString */
#define GCX_NAMESPACE           JSTRACE_NAMESPACE   /* JSXMLNamespace */
#define GCX_QNAME               JSTRACE_QNAME       /* JSXMLQName */
#define GCX_XML                 JSTRACE_XML         /* JSXML */
#define GCX_EXTERNAL_STRING     JSTRACE_LIMIT       /* JSString with external
                                                       chars */
/*
 * The number of defined GC types.
 */
#define GCX_NTYPES              (GCX_EXTERNAL_STRING + 8)

/*
 * The maximum limit for the number of GC types.
 */
#define GCX_LIMIT_LOG2         4           /* type index bits */
#define GCX_LIMIT              JS_BIT(GCX_LIMIT_LOG2)

JS_STATIC_ASSERT(GCX_NTYPES <= GCX_LIMIT);

/* GC flag definitions, must fit in 8 bits (type index goes in the low bits). */
#define GCF_TYPEMASK    JS_BITMASK(GCX_LIMIT_LOG2)
#define GCF_MARK        JS_BIT(GCX_LIMIT_LOG2)
#define GCF_FINAL       JS_BIT(GCX_LIMIT_LOG2 + 1)
#define GCF_LOCKSHIFT   (GCX_LIMIT_LOG2 + 2)   /* lock bit shift */
#define GCF_LOCK        JS_BIT(GCF_LOCKSHIFT)   /* lock request bit in API */

/*
 * Get the type of the external string or -1 if the string was not created
 * with JS_NewExternalString.
 */
extern intN
js_GetExternalStringGCType(JSString *str);

extern JS_FRIEND_API(uint32)
js_GetGCThingTraceKind(void *thing);

/*
 * The sole purpose of the function is to preserve public API compatibility
 * in JS_GetStringBytes which takes only single JSString* argument.
 */
JSRuntime*
js_GetGCStringRuntime(JSString *str);

#if 1
/*
 * Since we're forcing a GC from JS_GC anyway, don't bother wasting cycles
 * loading oldval.  XXX remove implied force, fix jsinterp.c's "second arg
 * ignored", etc.
 */
#define GC_POKE(cx, oldval) ((cx)->runtime->gcPoke = JS_TRUE)
#else
#define GC_POKE(cx, oldval) ((cx)->runtime->gcPoke = JSVAL_IS_GCTHING(oldval))
#endif

/*
 * Write barrier macro monitoring property update from oldval to newval in
 * scope->object.
 *
 * Since oldval is used only for the branded scope case, and the oldval actual
 * argument expression is typically not used otherwise by callers, performance
 * benefits if oldval is *not* evaluated into a callsite temporary variable,
 * and instead passed to GC_WRITE_BARRIER for conditional evaluation (we rely
 * on modern compilers to do a good CSE job). Yay, C macros.
 */
#define GC_WRITE_BARRIER(cx,scope,oldval,newval)                              \
    JS_BEGIN_MACRO                                                            \
        if (SCOPE_IS_BRANDED(scope) &&                                        \
            (oldval) != (newval) &&                                           \
            (VALUE_IS_FUNCTION(cx,oldval) || VALUE_IS_FUNCTION(cx,newval))) { \
            SCOPE_MAKE_UNIQUE_SHAPE(cx, scope);                               \
        }                                                                     \
        GC_POKE(cx, oldval);                                                  \
    JS_END_MACRO

extern JSBool
js_InitGC(JSRuntime *rt, uint32 maxbytes);

extern void
js_FinishGC(JSRuntime *rt);

extern intN
js_ChangeExternalStringFinalizer(JSStringFinalizeOp oldop,
                                 JSStringFinalizeOp newop);

extern JSBool
js_AddRoot(JSContext *cx, void *rp, const char *name);

extern JSBool
js_AddRootRT(JSRuntime *rt, void *rp, const char *name);

extern JSBool
js_RemoveRoot(JSRuntime *rt, void *rp);

#ifdef DEBUG
extern void
js_DumpNamedRoots(JSRuntime *rt,
                  void (*dump)(const char *name, void *rp, void *data),
                  void *data);
#endif

extern uint32
js_MapGCRoots(JSRuntime *rt, JSGCRootMapFun map, void *data);

/* Table of pointers with count valid members. */
typedef struct JSPtrTable {
    size_t      count;
    void        **array;
} JSPtrTable;

extern JSBool
js_RegisterCloseableIterator(JSContext *cx, JSObject *obj);

/*
 * The private JSGCThing struct, which describes a gcFreeList element.
 */
struct JSGCThing {
    JSGCThing   *next;
    uint8       *flagp;
};

#define GC_NBYTES_MAX           (10 * sizeof(JSGCThing))
#define GC_NUM_FREELISTS        (GC_NBYTES_MAX / sizeof(JSGCThing))
#define GC_FREELIST_NBYTES(i)   (((i) + 1) * sizeof(JSGCThing))
#define GC_FREELIST_INDEX(n)    (((n) / sizeof(JSGCThing)) - 1)

/*
 * Allocates a new GC thing of the given size. After a successful allocation
 * the caller must fully initialize the thing before calling any function that
 * can potentially trigger GC. This will ensure that GC tracing never sees junk
 * values stored in the partially initialized thing.
 */
extern void *
js_NewGCThing(JSContext *cx, uintN flags, size_t nbytes);

/*
 * Allocate a new double jsval and store the result in *vp. vp must be a root.
 * The function does not copy the result into any weak root.
 */
extern JSBool
js_NewDoubleInRootedValue(JSContext *cx, jsdouble d, jsval *vp);

/*
 * Return a pointer to a new GC-allocated and weakly-rooted jsdouble number,
 * or null when the allocation fails.
 */
extern jsdouble *
js_NewWeaklyRootedDouble(JSContext *cx, jsdouble d);

extern JSBool
js_LockGCThingRT(JSRuntime *rt, void *thing);

extern JSBool
js_UnlockGCThingRT(JSRuntime *rt, void *thing);

extern JSBool
js_IsAboutToBeFinalized(JSContext *cx, void *thing);

/*
 * Macro to test if a traversal is the marking phase of GC to avoid exposing
 * ScriptFilenameEntry to traversal implementations.
 */
#define IS_GC_MARKING_TRACER(trc) ((trc)->callback == NULL)

#if JS_HAS_XML_SUPPORT
# define JS_IS_VALID_TRACE_KIND(kind) ((uint32)(kind) <= JSTRACE_XML)
#else
# define JS_IS_VALID_TRACE_KIND(kind) ((uint32)(kind) <= JSTRACE_STRING)
#endif

/*
 * JS_IS_VALID_TRACE_KIND assumes that JSTRACE_STRING is the last non-xml
 * trace kind when JS_HAS_XML_SUPPORT is false.
 */
JS_STATIC_ASSERT(JSTRACE_STRING + 1 == JSTRACE_NAMESPACE);

/*
 * Trace jsval when JSVAL_IS_OBJECT(v) can be an arbitrary GC thing casted as
 * JSVAL_OBJECT and js_GetGCThingTraceKind has to be used to find the real
 * type behind v.
 */
extern void
js_CallValueTracerIfGCThing(JSTracer *trc, jsval v);

extern void
js_TraceStackFrame(JSTracer *trc, JSStackFrame *fp);

extern void
js_TraceRuntime(JSTracer *trc, JSBool allAtoms);

extern JS_FRIEND_API(void)
js_TraceContext(JSTracer *trc, JSContext *acx);

/*
 * Kinds of js_GC invocation.
 */
typedef enum JSGCInvocationKind {
    /* Normal invocation. */
    GC_NORMAL           = 0,

    /*
     * Called from js_DestroyContext for last JSContext in a JSRuntime, when
     * it is imperative that rt->gcPoke gets cleared early in js_GC.
     */
    GC_LAST_CONTEXT     = 1,

    /*
     * Flag bit telling js_GC that the caller has already acquired rt->gcLock.
     * Currently, this flag is set for the invocation kinds that also preserve
     * atoms and weak roots, so we don't need another bit for GC_KEEP_ATOMS.
     */
    GC_LOCK_HELD        = 0x10,
    GC_KEEP_ATOMS       = GC_LOCK_HELD,

    /*
     * Called from js_SetProtoOrParent with a request to set an object's proto
     * or parent slot inserted on rt->setSlotRequests.
     */
    GC_SET_SLOT_REQUEST = GC_LOCK_HELD | 1,

    /*
     * Called from js_NewGCThing as a last-ditch GC attempt. See comments
     * in jsgc.c just before js_GC's definition for details.
     */
    GC_LAST_DITCH       = GC_LOCK_HELD | 2
} JSGCInvocationKind;

extern void
js_GC(JSContext *cx, JSGCInvocationKind gckind);


/*
 * This function must be called with the GC lock held. It is a helper for code
 * that can potentially run outside JS request to ensure that the GC is not
 * running when the function returns.
 */
#ifdef JS_THREADSAFE
extern void
js_WaitForGC(JSRuntime *rt);
#else
# define js_WaitForGC(rt)    ((void) 0)
#endif


/* Call this after succesful malloc of memory for GC-related things. */
extern void
js_UpdateMallocCounter(JSContext *cx, size_t nbytes);

typedef struct JSGCArenaInfo JSGCArenaInfo;
typedef struct JSGCArenaList JSGCArenaList;
typedef struct JSGCChunkInfo JSGCChunkInfo;

struct JSGCArenaList {
    JSGCArenaInfo   *last;          /* last allocated GC arena */
    uint16          lastCount;      /* number of allocated things in the last
                                       arena */
    uint16          thingSize;      /* size of things to allocate on this list
                                     */
    JSGCThing       *freeList;      /* list of free GC things */
};

typedef union JSGCDoubleCell JSGCDoubleCell;

union JSGCDoubleCell {
    double          number;
    JSGCDoubleCell  *link;
};

JS_STATIC_ASSERT(sizeof(JSGCDoubleCell) == sizeof(double));

typedef struct JSGCDoubleArenaList {
    JSGCArenaInfo   *first;             /* first allocated GC arena */
    jsbitmap        *nextDoubleFlags;   /* bitmask with flags to check for free
                                           things */
} JSGCDoubleArenaList;

struct JSWeakRoots {
    /* Most recently created things by type, members of the GC's root set. */
    void            *newborn[GCX_NTYPES];

    /* Atom root for the last-looked-up atom on this context. */
    jsval           lastAtom;

    /* Root for the result of the most recent js_InternalInvoke call. */
    jsval           lastInternalResult;
};

JS_STATIC_ASSERT(JSVAL_NULL == 0);
#define JS_CLEAR_WEAK_ROOTS(wr) (memset((wr), 0, sizeof(JSWeakRoots)))

#ifdef DEBUG_notme
#define JS_GCMETER 1
#endif

#ifdef JS_GCMETER

typedef struct JSGCArenaStats {
    uint32  alloc;          /* allocation attempts */
    uint32  localalloc;     /* allocations from local lists */
    uint32  retry;          /* allocation retries after running the GC */
    uint32  fail;           /* allocation failures */
    uint32  nthings;        /* live GC things */
    uint32  maxthings;      /* maximum of live GC cells */
    double  totalthings;    /* live GC things the GC scanned so far */
    uint32  narenas;        /* number of arena in list before the GC */
    uint32  newarenas;      /* new arenas allocated before the last GC */
    uint32  livearenas;     /* number of live arenas after the last GC */
    uint32  maxarenas;      /* maximum of allocated arenas */
    uint32  totalarenas;    /* total number of arenas with live things that
                               GC scanned so far */
} JSGCArenaStats;

typedef struct JSGCStats {
    uint32  finalfail;  /* finalizer calls allocator failures */
    uint32  lockborn;   /* things born locked */
    uint32  lock;       /* valid lock calls */
    uint32  unlock;     /* valid unlock calls */
    uint32  depth;      /* mark tail recursion depth */
    uint32  maxdepth;   /* maximum mark tail recursion depth */
    uint32  cdepth;     /* mark recursion depth of C functions */
    uint32  maxcdepth;  /* maximum mark recursion depth of C functions */
    uint32  untraced;   /* number of times tracing of GC thing's children were
                           delayed due to a low C stack */
#ifdef DEBUG
    uint32  maxuntraced;/* maximum number of things with children to trace
                           later */
#endif
    uint32  maxlevel;   /* maximum GC nesting (indirect recursion) level */
    uint32  poke;       /* number of potentially useful GC calls */
    uint32  afree;      /* thing arenas freed so far */
    uint32  stackseg;   /* total extraordinary stack segments scanned */
    uint32  segslots;   /* total stack segment jsval slots scanned */
    uint32  nclose;     /* number of objects with close hooks */
    uint32  maxnclose;  /* max number of objects with close hooks */
    uint32  closelater; /* number of close hooks scheduled to run */
    uint32  maxcloselater; /* max number of close hooks scheduled to run */

    JSGCArenaStats  arenaStats[GC_NUM_FREELISTS];
    JSGCArenaStats  doubleArenaStats;
} JSGCStats;

extern JS_FRIEND_API(void)
js_DumpGCStats(JSRuntime *rt, FILE *fp);

#endif /* JS_GCMETER */

JS_END_EXTERN_C

#endif /* jsgc_h___ */