github.com/rohankumardubey/syslog-redirector-golang@v0.0.0-20140320174030-4859f03d829a/src/pkg/runtime/mcache.c (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Per-P malloc cache for small objects.
     6  //
     7  // See malloc.h for an overview.
     8  
     9  #include "runtime.h"
    10  #include "arch_GOARCH.h"
    11  #include "malloc.h"
    12  
    13  void
    14  runtime·MCache_Refill(MCache *c, int32 sizeclass)
    15  {
    16  	MCacheList *l;
    17  
    18  	// Replenish using central lists.
    19  	l = &c->list[sizeclass];
    20  	if(l->list)
    21  		runtime·throw("MCache_Refill: the list is not empty");
    22  	l->nlist = runtime·MCentral_AllocList(&runtime·mheap.central[sizeclass], &l->list);
    23  	if(l->list == nil)
    24  		runtime·throw("out of memory");
    25  }
    26  
    27  // Take n elements off l and return them to the central free list.
    28  static void
    29  ReleaseN(MCacheList *l, int32 n, int32 sizeclass)
    30  {
    31  	MLink *first, **lp;
    32  	int32 i;
    33  
    34  	// Cut off first n elements.
    35  	first = l->list;
    36  	lp = &l->list;
    37  	for(i=0; i<n; i++)
    38  		lp = &(*lp)->next;
    39  	l->list = *lp;
    40  	*lp = nil;
    41  	l->nlist -= n;
    42  
    43  	// Return them to central free list.
    44  	runtime·MCentral_FreeList(&runtime·mheap.central[sizeclass], first);
    45  }
    46  
    47  void
    48  runtime·MCache_Free(MCache *c, void *v, int32 sizeclass, uintptr size)
    49  {
    50  	MCacheList *l;
    51  	MLink *p;
    52  
    53  	// Put back on list.
    54  	l = &c->list[sizeclass];
    55  	p = v;
    56  	p->next = l->list;
    57  	l->list = p;
    58  	l->nlist++;
    59  	c->local_cachealloc -= size;
    60  
    61  	// We transfer span at a time from MCentral to MCache,
    62  	// if we have 2 times more than that, release a half back.
    63  	if(l->nlist >= 2*(runtime·class_to_allocnpages[sizeclass]<<PageShift)/size)
    64  		ReleaseN(l, l->nlist/2, sizeclass);
    65  }
    66  
    67  void
    68  runtime·MCache_ReleaseAll(MCache *c)
    69  {
    70  	int32 i;
    71  	MCacheList *l;
    72  
    73  	for(i=0; i<NumSizeClasses; i++) {
    74  		l = &c->list[i];
    75  		if(l->list) {
    76  			runtime·MCentral_FreeList(&runtime·mheap.central[i], l->list);
    77  			l->list = nil;
    78  			l->nlist = 0;
    79  		}
    80  	}
    81  }