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-rw-r--r--src/malloc/mallocng/malloc.c387
1 files changed, 387 insertions, 0 deletions
diff --git a/src/malloc/mallocng/malloc.c b/src/malloc/mallocng/malloc.c
new file mode 100644
index 00000000..d695ab8e
--- /dev/null
+++ b/src/malloc/mallocng/malloc.c
@@ -0,0 +1,387 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <errno.h>
+
+#include "meta.h"
+
+LOCK_OBJ_DEF;
+
+const uint16_t size_classes[] = {
+ 1, 2, 3, 4, 5, 6, 7, 8,
+ 9, 10, 12, 15,
+ 18, 20, 25, 31,
+ 36, 42, 50, 63,
+ 72, 84, 102, 127,
+ 146, 170, 204, 255,
+ 292, 340, 409, 511,
+ 584, 682, 818, 1023,
+ 1169, 1364, 1637, 2047,
+ 2340, 2730, 3276, 4095,
+ 4680, 5460, 6552, 8191,
+};
+
+static const uint8_t small_cnt_tab[][3] = {
+ { 30, 30, 30 },
+ { 31, 15, 15 },
+ { 20, 10, 10 },
+ { 31, 15, 7 },
+ { 25, 12, 6 },
+ { 21, 10, 5 },
+ { 18, 8, 4 },
+ { 31, 15, 7 },
+ { 28, 14, 6 },
+};
+
+static const uint8_t med_cnt_tab[4] = { 28, 24, 20, 32 };
+
+struct malloc_context ctx = { 0 };
+
+struct meta *alloc_meta(void)
+{
+ struct meta *m;
+ unsigned char *p;
+ if (!ctx.init_done) {
+#ifndef PAGESIZE
+ ctx.pagesize = get_page_size();
+#endif
+ ctx.secret = get_random_secret();
+ ctx.init_done = 1;
+ }
+ size_t pagesize = PGSZ;
+ if (pagesize < 4096) pagesize = 4096;
+ if ((m = dequeue_head(&ctx.free_meta_head))) return m;
+ if (!ctx.avail_meta_count) {
+ int need_unprotect = 1;
+ if (!ctx.avail_meta_area_count && ctx.brk!=-1) {
+ uintptr_t new = ctx.brk + pagesize;
+ int need_guard = 0;
+ if (!ctx.brk) {
+ need_guard = 1;
+ ctx.brk = brk(0);
+ // some ancient kernels returned _ebss
+ // instead of next page as initial brk.
+ ctx.brk += -ctx.brk & (pagesize-1);
+ new = ctx.brk + 2*pagesize;
+ }
+ if (brk(new) != new) {
+ ctx.brk = -1;
+ } else {
+ if (need_guard) mmap((void *)ctx.brk, pagesize,
+ PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
+ ctx.brk = new;
+ ctx.avail_meta_areas = (void *)(new - pagesize);
+ ctx.avail_meta_area_count = pagesize>>12;
+ need_unprotect = 0;
+ }
+ }
+ if (!ctx.avail_meta_area_count) {
+ size_t n = 2UL << ctx.meta_alloc_shift;
+ p = mmap(0, n*pagesize, PROT_NONE,
+ MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (p==MAP_FAILED) return 0;
+ ctx.avail_meta_areas = p + pagesize;
+ ctx.avail_meta_area_count = (n-1)*(pagesize>>12);
+ ctx.meta_alloc_shift++;
+ }
+ p = ctx.avail_meta_areas;
+ if ((uintptr_t)p & (pagesize-1)) need_unprotect = 0;
+ if (need_unprotect)
+ if (mprotect(p, pagesize, PROT_READ|PROT_WRITE)
+ && errno != ENOSYS)
+ return 0;
+ ctx.avail_meta_area_count--;
+ ctx.avail_meta_areas = p + 4096;
+ if (ctx.meta_area_tail) {
+ ctx.meta_area_tail->next = (void *)p;
+ } else {
+ ctx.meta_area_head = (void *)p;
+ }
+ ctx.meta_area_tail = (void *)p;
+ ctx.meta_area_tail->check = ctx.secret;
+ ctx.avail_meta_count = ctx.meta_area_tail->nslots
+ = (4096-sizeof(struct meta_area))/sizeof *m;
+ ctx.avail_meta = ctx.meta_area_tail->slots;
+ }
+ ctx.avail_meta_count--;
+ m = ctx.avail_meta++;
+ m->prev = m->next = 0;
+ return m;
+}
+
+static uint32_t try_avail(struct meta **pm)
+{
+ struct meta *m = *pm;
+ uint32_t first;
+ if (!m) return 0;
+ uint32_t mask = m->avail_mask;
+ if (!mask) {
+ if (!m) return 0;
+ if (!m->freed_mask) {
+ dequeue(pm, m);
+ m = *pm;
+ if (!m) return 0;
+ } else {
+ m = m->next;
+ *pm = m;
+ }
+
+ mask = m->freed_mask;
+
+ // skip fully-free group unless it's the only one
+ // or it's a permanently non-freeable group
+ if (mask == (2u<<m->last_idx)-1 && m->freeable) {
+ m = m->next;
+ *pm = m;
+ mask = m->freed_mask;
+ }
+
+ // activate more slots in a not-fully-active group
+ // if needed, but only as a last resort. prefer using
+ // any other group with free slots. this avoids
+ // touching & dirtying as-yet-unused pages.
+ if (!(mask & ((2u<<m->mem->active_idx)-1))) {
+ if (m->next != m) {
+ m = m->next;
+ *pm = m;
+ } else {
+ int cnt = m->mem->active_idx + 2;
+ int size = size_classes[m->sizeclass]*UNIT;
+ int span = UNIT + size*cnt;
+ // activate up to next 4k boundary
+ while ((span^(span+size-1)) < 4096) {
+ cnt++;
+ span += size;
+ }
+ if (cnt > m->last_idx+1)
+ cnt = m->last_idx+1;
+ m->mem->active_idx = cnt-1;
+ }
+ }
+ mask = activate_group(m);
+ assert(mask);
+ decay_bounces(m->sizeclass);
+ }
+ first = mask&-mask;
+ m->avail_mask = mask-first;
+ return first;
+}
+
+static int alloc_slot(int, size_t);
+
+static struct meta *alloc_group(int sc, size_t req)
+{
+ size_t size = UNIT*size_classes[sc];
+ int i = 0, cnt;
+ unsigned char *p;
+ struct meta *m = alloc_meta();
+ if (!m) return 0;
+ size_t usage = ctx.usage_by_class[sc];
+ size_t pagesize = PGSZ;
+ int active_idx;
+ if (sc < 9) {
+ while (i<2 && 4*small_cnt_tab[sc][i] > usage)
+ i++;
+ cnt = small_cnt_tab[sc][i];
+ } else {
+ // lookup max number of slots fitting in power-of-two size
+ // from a table, along with number of factors of two we
+ // can divide out without a remainder or reaching 1.
+ cnt = med_cnt_tab[sc&3];
+
+ // reduce cnt to avoid excessive eagar allocation.
+ while (!(cnt&1) && 4*cnt > usage)
+ cnt >>= 1;
+
+ // data structures don't support groups whose slot offsets
+ // in units don't fit in 16 bits.
+ while (size*cnt >= 65536*UNIT)
+ cnt >>= 1;
+ }
+
+ // If we selected a count of 1 above but it's not sufficient to use
+ // mmap, increase to 2. Then it might be; if not it will nest.
+ if (cnt==1 && size*cnt+UNIT <= pagesize/2) cnt = 2;
+
+ // All choices of size*cnt are "just below" a power of two, so anything
+ // larger than half the page size should be allocated as whole pages.
+ if (size*cnt+UNIT > pagesize/2) {
+ // check/update bounce counter to start/increase retention
+ // of freed maps, and inhibit use of low-count, odd-size
+ // small mappings and single-slot groups if activated.
+ int nosmall = is_bouncing(sc);
+ account_bounce(sc);
+ step_seq();
+
+ // since the following count reduction opportunities have
+ // an absolute memory usage cost, don't overdo them. count
+ // coarse usage as part of usage.
+ if (!(sc&1) && sc<32) usage += ctx.usage_by_class[sc+1];
+
+ // try to drop to a lower count if the one found above
+ // increases usage by more than 25%. these reduced counts
+ // roughly fill an integral number of pages, just not a
+ // power of two, limiting amount of unusable space.
+ if (4*cnt > usage && !nosmall) {
+ if (0);
+ else if ((sc&3)==1 && size*cnt>8*pagesize) cnt = 2;
+ else if ((sc&3)==2 && size*cnt>4*pagesize) cnt = 3;
+ else if ((sc&3)==0 && size*cnt>8*pagesize) cnt = 3;
+ else if ((sc&3)==0 && size*cnt>2*pagesize) cnt = 5;
+ }
+ size_t needed = size*cnt + UNIT;
+ needed += -needed & (pagesize-1);
+
+ // produce an individually-mmapped allocation if usage is low,
+ // bounce counter hasn't triggered, and either it saves memory
+ // or it avoids eagar slot allocation without wasting too much.
+ if (!nosmall && cnt<=7) {
+ req += IB + UNIT;
+ req += -req & (pagesize-1);
+ if (req<size+UNIT || (req>=4*pagesize && 2*cnt>usage)) {
+ cnt = 1;
+ needed = req;
+ }
+ }
+
+ p = mmap(0, needed, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (p==MAP_FAILED) {
+ free_meta(m);
+ return 0;
+ }
+ m->maplen = needed>>12;
+ ctx.mmap_counter++;
+ active_idx = (4096-UNIT)/size-1;
+ if (active_idx > cnt-1) active_idx = cnt-1;
+ if (active_idx < 0) active_idx = 0;
+ } else {
+ int j = size_to_class(UNIT+cnt*size-IB);
+ int idx = alloc_slot(j, UNIT+cnt*size-IB);
+ if (idx < 0) {
+ free_meta(m);
+ return 0;
+ }
+ struct meta *g = ctx.active[j];
+ p = enframe(g, idx, UNIT*size_classes[j]-IB, ctx.mmap_counter);
+ m->maplen = 0;
+ p[-3] = (p[-3]&31) | (6<<5);
+ for (int i=0; i<=cnt; i++)
+ p[UNIT+i*size-4] = 0;
+ active_idx = cnt-1;
+ }
+ ctx.usage_by_class[sc] += cnt;
+ m->avail_mask = (2u<<active_idx)-1;
+ m->freed_mask = (2u<<(cnt-1))-1 - m->avail_mask;
+ m->mem = (void *)p;
+ m->mem->meta = m;
+ m->mem->active_idx = active_idx;
+ m->last_idx = cnt-1;
+ m->freeable = 1;
+ m->sizeclass = sc;
+ return m;
+}
+
+static int alloc_slot(int sc, size_t req)
+{
+ uint32_t first = try_avail(&ctx.active[sc]);
+ if (first) return a_ctz_32(first);
+
+ struct meta *g = alloc_group(sc, req);
+ if (!g) return -1;
+
+ g->avail_mask--;
+ queue(&ctx.active[sc], g);
+ return 0;
+}
+
+void *malloc(size_t n)
+{
+ if (size_overflows(n)) return 0;
+ struct meta *g;
+ uint32_t mask, first;
+ int sc;
+ int idx;
+ int ctr;
+
+ if (n >= MMAP_THRESHOLD) {
+ size_t needed = n + IB + UNIT;
+ void *p = mmap(0, needed, PROT_READ|PROT_WRITE,
+ MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (p==MAP_FAILED) return 0;
+ wrlock();
+ step_seq();
+ g = alloc_meta();
+ if (!g) {
+ unlock();
+ munmap(p, needed);
+ return 0;
+ }
+ g->mem = p;
+ g->mem->meta = g;
+ g->last_idx = 0;
+ g->freeable = 1;
+ g->sizeclass = 63;
+ g->maplen = (needed+4095)/4096;
+ g->avail_mask = g->freed_mask = 0;
+ // use a global counter to cycle offset in
+ // individually-mmapped allocations.
+ ctx.mmap_counter++;
+ idx = 0;
+ goto success;
+ }
+
+ sc = size_to_class(n);
+
+ rdlock();
+ g = ctx.active[sc];
+
+ // use coarse size classes initially when there are not yet
+ // any groups of desired size. this allows counts of 2 or 3
+ // to be allocated at first rather than having to start with
+ // 7 or 5, the min counts for even size classes.
+ if (!g && sc>=4 && sc<32 && sc!=6 && !(sc&1) && !ctx.usage_by_class[sc]) {
+ size_t usage = ctx.usage_by_class[sc|1];
+ // if a new group may be allocated, count it toward
+ // usage in deciding if we can use coarse class.
+ if (!ctx.active[sc|1] || (!ctx.active[sc|1]->avail_mask
+ && !ctx.active[sc|1]->freed_mask))
+ usage += 3;
+ if (usage <= 12)
+ sc |= 1;
+ g = ctx.active[sc];
+ }
+
+ for (;;) {
+ mask = g ? g->avail_mask : 0;
+ first = mask&-mask;
+ if (!first) break;
+ if (RDLOCK_IS_EXCLUSIVE || !MT)
+ g->avail_mask = mask-first;
+ else if (a_cas(&g->avail_mask, mask, mask-first)!=mask)
+ continue;
+ idx = a_ctz_32(first);
+ goto success;
+ }
+ upgradelock();
+
+ idx = alloc_slot(sc, n);
+ if (idx < 0) {
+ unlock();
+ return 0;
+ }
+ g = ctx.active[sc];
+
+success:
+ ctr = ctx.mmap_counter;
+ unlock();
+ return enframe(g, idx, n, ctr);
+}
+
+int is_allzero(void *p)
+{
+ struct meta *g = get_meta(p);
+ return g->sizeclass >= 48 ||
+ get_stride(g) < UNIT*size_classes[g->sizeclass];
+}