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Commit 7f9d9565 authored by Rusty Russell's avatar Rusty Russell
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alloc: first cut of tiny allocator (down to 2 bytes!)

parent d707abbb
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Inline Side-by-side
Showing with 637 additions and 239 deletions
ccan/alloc/alloc.c
View file @ 7f9d9565
......@@ -5,6 +5,8 @@
#include <assert.h>
#include <stdlib.h>
#include "alloc.h"
#include "bitops.h"
#include "tiny.h"
#include <ccan/build_assert/build_assert.h>
#include <ccan/likely/likely.h>
#include <ccan/short_types/short_types.h>
......@@ -91,146 +93,6 @@ struct page_header {
unsigned long used[1]; /* One bit per element. */
};
/* 2 bit for every byte to allocate. */
static void tiny_alloc_init(void *pool, unsigned long poolsize)
{
/* FIXME */
}
static void *tiny_alloc_get(void *pool, unsigned long poolsize,
unsigned long size, unsigned long align)
{
/* FIXME */
return NULL;
}
static void tiny_alloc_free(void *pool, unsigned long poolsize, void *free)
{
/* FIXME */
}
static unsigned long tiny_alloc_size(void *pool, unsigned long poolsize,
void *p)
{
/* FIXME */
return 0;
}
static bool tiny_alloc_check(void *pool, unsigned long poolsize)
{
/* FIXME */
return true;
}
static unsigned int fls(unsigned long val)
{
#if HAVE_BUILTIN_CLZL
/* This is significantly faster! */
return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
#else
unsigned int r = 32;
if (!val)
return 0;
if (!(val & 0xffff0000u)) {
val <<= 16;
r -= 16;
}
if (!(val & 0xff000000u)) {
val <<= 8;
r -= 8;
}
if (!(val & 0xf0000000u)) {
val <<= 4;
r -= 4;
}
if (!(val & 0xc0000000u)) {
val <<= 2;
r -= 2;
}
if (!(val & 0x80000000u)) {
val <<= 1;
r -= 1;
}
return r;
#endif
}
/* FIXME: Move to bitops. */
static unsigned int ffsl(unsigned long val)
{
#if HAVE_BUILTIN_FFSL
/* This is significantly faster! */
return __builtin_ffsl(val);
#else
unsigned int r = 1;
if (!val)
return 0;
if (sizeof(long) == sizeof(u64)) {
if (!(val & 0xffffffff)) {
/* Workaround gcc warning on 32-bit:
error: right shift count >= width of type */
u64 tmp = val;
tmp >>= 32;
val = tmp;
r += 32;
}
}
if (!(val & 0xffff)) {
val >>= 16;
r += 16;
}
if (!(val & 0xff)) {
val >>= 8;
r += 8;
}
if (!(val & 0xf)) {
val >>= 4;
r += 4;
}
if (!(val & 3)) {
val >>= 2;
r += 2;
}
if (!(val & 1)) {
val >>= 1;
r += 1;
}
return r;
#endif
}
static unsigned int popcount(unsigned long val)
{
#if HAVE_BUILTIN_POPCOUNTL
return __builtin_popcountl(val);
#else
if (sizeof(long) == sizeof(u64)) {
u64 v = val;
v = (v & 0x5555555555555555ULL)
+ ((v >> 1) & 0x5555555555555555ULL);
v = (v & 0x3333333333333333ULL)
+ ((v >> 1) & 0x3333333333333333ULL);
v = (v & 0x0F0F0F0F0F0F0F0FULL)
+ ((v >> 1) & 0x0F0F0F0F0F0F0F0FULL);
v = (v & 0x00FF00FF00FF00FFULL)
+ ((v >> 1) & 0x00FF00FF00FF00FFULL);
v = (v & 0x0000FFFF0000FFFFULL)
+ ((v >> 1) & 0x0000FFFF0000FFFFULL);
v = (v & 0x00000000FFFFFFFFULL)
+ ((v >> 1) & 0x00000000FFFFFFFFULL);
return v;
}
val = (val & 0x55555555ULL) + ((val >> 1) & 0x55555555ULL);
val = (val & 0x33333333ULL) + ((val >> 1) & 0x33333333ULL);
val = (val & 0x0F0F0F0FULL) + ((val >> 1) & 0x0F0F0F0FULL);
val = (val & 0x00FF00FFULL) + ((val >> 1) & 0x00FF00FFULL);
val = (val & 0x0000FFFFULL) + ((val >> 1) & 0x0000FFFFULL);
return val;
#endif
}
/*
* Every 4 buckets, the size doubles.
* Between buckets, sizes increase linearly.
......@@ -274,11 +136,6 @@ static unsigned int small_page_bits(unsigned long poolsize)
return fls(poolsize / MAX_SMALL_PAGES / 2);
}
static unsigned long align_up(unsigned long x, unsigned long align)
{
return (x + align - 1) & ~(align - 1);
}
static struct page_header *from_pgnum(struct header *head,
unsigned long pgnum,
unsigned sp_bits)
......@@ -1051,10 +908,6 @@ static unsigned long visualize_bucket(FILE *out, struct header *head,
return overhead;
}
static void tiny_alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
{
}
void alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
{
struct header *head = pool;
......
ccan/alloc/bitops.c 0 → 100644
View file @ 7f9d9565
#include "bitops.h"
#include "config.h"
#include <ccan/short_types/short_types.h>
#include <limits.h>
unsigned int fls(unsigned long val)
{
#if HAVE_BUILTIN_CLZL
/* This is significantly faster! */
return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
#else
unsigned int r = 32;
if (!val)
return 0;
if (!(val & 0xffff0000u)) {
val <<= 16;
r -= 16;
}
if (!(val & 0xff000000u)) {
val <<= 8;
r -= 8;
}
if (!(val & 0xf0000000u)) {
val <<= 4;
r -= 4;
}
if (!(val & 0xc0000000u)) {
val <<= 2;
r -= 2;
}
if (!(val & 0x80000000u)) {
val <<= 1;
r -= 1;
}
return r;
#endif
}
/* FIXME: Move to bitops. */
unsigned int ffsl(unsigned long val)
{
#if HAVE_BUILTIN_FFSL
/* This is significantly faster! */
return __builtin_ffsl(val);
#else
unsigned int r = 1;
if (!val)
return 0;
if (sizeof(long) == sizeof(u64)) {
if (!(val & 0xffffffff)) {
/* Workaround gcc warning on 32-bit:
error: right shift count >= width of type */
u64 tmp = val;
tmp >>= 32;
val = tmp;
r += 32;
}
}
if (!(val & 0xffff)) {
val >>= 16;
r += 16;
}
if (!(val & 0xff)) {
val >>= 8;
r += 8;
}
if (!(val & 0xf)) {
val >>= 4;
r += 4;
}
if (!(val & 3)) {
val >>= 2;
r += 2;
}
if (!(val & 1)) {
val >>= 1;
r += 1;
}
return r;
#endif
}
unsigned int popcount(unsigned long val)
{
#if HAVE_BUILTIN_POPCOUNTL
return __builtin_popcountl(val);
#else
if (sizeof(long) == sizeof(u64)) {
u64 v = val;
v = (v & 0x5555555555555555ULL)
+ ((v >> 1) & 0x5555555555555555ULL);
v = (v & 0x3333333333333333ULL)
+ ((v >> 1) & 0x3333333333333333ULL);
v = (v & 0x0F0F0F0F0F0F0F0FULL)
+ ((v >> 1) & 0x0F0F0F0F0F0F0F0FULL);
v = (v & 0x00FF00FF00FF00FFULL)
+ ((v >> 1) & 0x00FF00FF00FF00FFULL);
v = (v & 0x0000FFFF0000FFFFULL)
+ ((v >> 1) & 0x0000FFFF0000FFFFULL);
v = (v & 0x00000000FFFFFFFFULL)
+ ((v >> 1) & 0x00000000FFFFFFFFULL);
return v;
}
val = (val & 0x55555555ULL) + ((val >> 1) & 0x55555555ULL);
val = (val & 0x33333333ULL) + ((val >> 1) & 0x33333333ULL);
val = (val & 0x0F0F0F0FULL) + ((val >> 1) & 0x0F0F0F0FULL);
val = (val & 0x00FF00FFULL) + ((val >> 1) & 0x00FF00FFULL);
val = (val & 0x0000FFFFULL) + ((val >> 1) & 0x0000FFFFULL);
return val;
#endif
}
unsigned long align_up(unsigned long x, unsigned long align)
{
return (x + align - 1) & ~(align - 1);
}
ccan/alloc/bitops.h 0 → 100644
View file @ 7f9d9565
#ifndef CCAN_ALLOC_BITOPS_H
#define CCAN_ALLOC_BITOPS_H
unsigned int fls(unsigned long val);
unsigned int ffsl(unsigned long val);
unsigned int popcount(unsigned long val);
unsigned long align_up(unsigned long x, unsigned long align);
#endif /* CCAN_ALLOC_BITOPS_H */
ccan/alloc/test/run-testsize.c
View file @ 7f9d9565
#include <ccan/alloc/alloc.h>
#include <ccan/tap/tap.h>
#include <ccan/alloc/alloc.c>
#include <ccan/alloc/bitops.c>
#include <ccan/alloc/tiny.c>
#include <stdlib.h>
#include <stdbool.h>
#include <err.h>
#define POOL_ORD 16
#define POOL_SIZE (1 << POOL_ORD)
static void invert_bytes(unsigned char *p, unsigned long size)
{
unsigned int i;
......@@ -21,49 +20,62 @@ static bool sizes_ok(void *mem, unsigned long poolsize, void *p[], unsigned num)
unsigned int i;
for (i = 0; i < num; i++)
if (alloc_size(mem, poolsize, p[i]) < i)
if (p[i] && alloc_size(mem, poolsize, p[i]) < i)
return false;
return true;
}
int main(int argc, char *argv[])
static void test_pool(unsigned long pool_size)
{
unsigned int i, j, num;
void *mem;
unsigned int i, num;
void *p[POOL_SIZE];
plan_tests(5);
void **p;
bool flip = false;
/* FIXME: Needs to be page aligned for now. */
if (posix_memalign(&mem, 1 << POOL_ORD, POOL_SIZE) != 0)
errx(1, "Failed allocating aligned memory");
p = calloc(pool_size, sizeof(void *));
mem = malloc(pool_size);
alloc_init(mem, POOL_SIZE);
alloc_init(mem, pool_size);
/* Check that alloc_size() gives reasonable answers. */
for (i = 0; i < POOL_SIZE; i++) {
p[i] = alloc_get(mem, POOL_SIZE, i, 1);
for (i = 0; i < pool_size; i = i * 3 / 2 + 1) {
p[i] = alloc_get(mem, pool_size, i, 1);
if (!p[i])
break;
invert_bytes(p[i], alloc_size(mem, POOL_SIZE, p[i]));
invert_bytes(p[i], alloc_size(mem, pool_size, p[i]));
}
ok1(i < POOL_SIZE);
ok1(i < pool_size);
num = i;
ok1(alloc_check(mem, POOL_SIZE));
ok1(sizes_ok(mem, POOL_SIZE, p, num));
ok1(alloc_check(mem, pool_size));
ok1(sizes_ok(mem, pool_size, p, num));
/* Free every second one. */
for (i = 0; i < num; i+=2) {
alloc_free(mem, POOL_SIZE, p[i]);
/* Compact. */
if (i + 1 < num) {
p[i/2] = p[i + 1];
invert_bytes(p[i/2], alloc_size(mem,POOL_SIZE,p[i/2]));
for (i = j = 0; i < num; i = i * 3 / 2 + 1) {
flip = !flip;
if (flip) {
/* Compact. */
p[j++] = p[i];
invert_bytes(p[i], alloc_size(mem,pool_size,p[i]));
continue;
}
alloc_free(mem, pool_size, p[i]);
}
num /= 2;
ok1(alloc_check(mem, POOL_SIZE));
ok1(sizes_ok(mem, POOL_SIZE, p, num));
ok1(alloc_check(mem, pool_size));
ok1(sizes_ok(mem, pool_size, p, num));
free(p);
free(mem);
}
int main(int argc, char *argv[])
{
plan_tests(10);
/* Large test. */
test_pool(MIN_USEFUL_SIZE * 2);
/* Small test. */
test_pool(MIN_USEFUL_SIZE / 2);
return exit_status();
}
ccan/alloc/test/run-tiny-encode.c 0 → 100644
View file @ 7f9d9565
#include <ccan/tap/tap.h>
#include "config.h"
#include <ccan/alloc/tiny.c>
#include <ccan/alloc/bitops.c>
#include <stdlib.h>
#include <err.h>
/* Test encoding and decoding. */
#define ARR_SIZE 10
int main(void)
{
unsigned char array[ARR_SIZE];
unsigned int i, prev;
plan_tests(567);
prev = 0;
/* Test encode_length */
for (i = 1; i < 0x8000000; i *= 2) {
ok1(encode_length(i-1) >= prev);
ok1(encode_length(i) >= encode_length(i-1));
ok1(encode_length(i+1) >= encode_length(i));
prev = encode_length(i);
}
/* Test it against actual encoding return val. */
for (i = 1; i < 0x8000000; i *= 2) {
ok1(encode_length(i-1) == encode(i - 1 + MIN_BLOCK_SIZE,
false, array, ARR_SIZE));
ok1(encode_length(i) == encode(i + MIN_BLOCK_SIZE,
false, array, ARR_SIZE));
ok1(encode_length(i+1) == encode(i + 1 + MIN_BLOCK_SIZE,
false, array, ARR_SIZE));
}
/* Test encoder vs. decoder. */
for (i = 1; i < 0x8000000; i *= 2) {
unsigned long hdrlen, len;
bool free;
hdrlen = encode(i - 1 + MIN_BLOCK_SIZE, false, array, ARR_SIZE);
ok1(decode(&len, &free, array) == hdrlen);
ok1(len == i - 1 + MIN_BLOCK_SIZE);
ok1(free == false);
hdrlen = encode(i + MIN_BLOCK_SIZE, true, array, ARR_SIZE);
ok1(decode(&len, &free, array) == hdrlen);
ok1(len == i + MIN_BLOCK_SIZE);
ok1(free == true);
hdrlen = encode(i + 1 + MIN_BLOCK_SIZE, true, array, ARR_SIZE);
ok1(decode(&len, &free, array) == hdrlen);
ok1(len == i + 1 + MIN_BLOCK_SIZE);
ok1(free == true);
}
/* Test encoder limit enforcement. */
for (i = 1; i < 0x8000000; i *= 2) {
unsigned char *arr;
unsigned int len;
/* These should fit. */
ok1(encode(i-1 + MIN_BLOCK_SIZE, false, array,
encode_length(i-1)) == encode_length(i-1));
ok1(encode(i + MIN_BLOCK_SIZE, false, array,
encode_length(i)) == encode_length(i));
ok1(encode(i+1 + MIN_BLOCK_SIZE, false, array,
encode_length(i+1)) == encode_length(i+1));
/* These should not: malloc so valgrind finds overruns. */
len = encode_length(i-1) - 1;
arr = malloc(len);
ok1(encode(i-1 + MIN_BLOCK_SIZE, true, arr, len) == 0);
free(arr);
len = encode_length(i-1) - 1;
arr = malloc(len);
ok1(encode(i + MIN_BLOCK_SIZE, false, arr, len) == 0);
free(arr);
len = encode_length(i+1) - 1;
arr = malloc(len);
ok1(encode(i+1 + MIN_BLOCK_SIZE, false, arr, len) == 0);
free(arr);
}
return exit_status();
}
ccan/alloc/test/run.c
View file @ 7f9d9565
#include <ccan/alloc/alloc.h>
#include <ccan/tap/tap.h>
#include <ccan/alloc/alloc.c>
#include <ccan/alloc/bitops.c>
#include <ccan/alloc/tiny.c>
#include <stdlib.h>
#include <err.h>
#define POOL_ORD 20
#define POOL_SIZE (1 << POOL_ORD)
#define sort(p, num, cmp) \
qsort((p), (num), sizeof(*p), (int(*)(const void *, const void *))cmp)
......@@ -25,35 +24,35 @@ static bool unique(void *p[], unsigned int num)
return true;
}
static bool free_every_second_one(void *mem, unsigned int num, void *p[])
static bool free_every_second_one(void *mem, unsigned int num,
unsigned long pool_size, void *p[])
{
unsigned int i;
/* Free every second one. */
for (i = 0; i < num; i += 2) {
alloc_free(mem, POOL_SIZE, p[i]);
alloc_free(mem, pool_size, p[i]);
}
if (!alloc_check(mem, POOL_SIZE))
if (!alloc_check(mem, pool_size))
return false;
for (i = 1; i < num; i += 2) {
alloc_free(mem, POOL_SIZE, p[i]);
alloc_free(mem, pool_size, p[i]);
}
if (!alloc_check(mem, POOL_SIZE))
if (!alloc_check(mem, pool_size))
return false;
return true;
}
int main(int argc, char *argv[])
static void test(unsigned int pool_size)
{
void *mem;
unsigned int i, num, max_size;
void **p = calloc(POOL_SIZE, sizeof(*p));
plan_tests(120);
void **p = calloc(pool_size, sizeof(*p));
/* FIXME: Should be pool_size! */
unsigned alloc_limit = (pool_size / MAX_LARGE_PAGES) >> MAX_PAGE_OBJECT_ORDER;
/* FIXME: Needs to be page aligned for now. */
if (posix_memalign(&mem, 1 << POOL_ORD, POOL_SIZE) != 0)
if (posix_memalign(&mem, pool_size, pool_size) != 0)
errx(1, "Failed allocating aligned memory");
/* Small pool, all allocs fail, even 0-length. */
......@@ -66,33 +65,33 @@ int main(int argc, char *argv[])
/* Free of NULL should work. */
alloc_free(mem, 0, NULL);
alloc_init(mem, POOL_SIZE);
ok1(alloc_check(mem, POOL_SIZE));
alloc_init(mem, pool_size);
ok1(alloc_check(mem, pool_size));
/* Find largest allocation which works. */
for (max_size = POOL_SIZE * 2; max_size; max_size--) {
p[0] = alloc_get(mem, POOL_SIZE, max_size, 1);
for (max_size = pool_size + 1; max_size; max_size--) {
p[0] = alloc_get(mem, pool_size, max_size, 1);
if (p[0])
break;
}
ok1(max_size < POOL_SIZE);
ok1(max_size < pool_size);
ok1(max_size > 0);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, POOL_SIZE, p[0]) >= max_size);
ok1(alloc_check(mem, pool_size));
ok1(alloc_size(mem, pool_size, p[0]) >= max_size);
/* Free it, should be able to reallocate it. */
alloc_free(mem, POOL_SIZE, p[0]);
ok1(alloc_check(mem, POOL_SIZE));
alloc_free(mem, pool_size, p[0]);
ok1(alloc_check(mem, pool_size));
p[0] = alloc_get(mem, POOL_SIZE, max_size, 1);
p[0] = alloc_get(mem, pool_size, max_size, 1);
ok1(p[0]);
ok1(alloc_size(mem, POOL_SIZE, p[0]) >= max_size);
ok1(alloc_check(mem, POOL_SIZE));
alloc_free(mem, POOL_SIZE, p[0]);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, pool_size, p[0]) >= max_size);
ok1(alloc_check(mem, pool_size));
alloc_free(mem, pool_size, p[0]);
ok1(alloc_check(mem, pool_size));
/* Allocate a whole heap. */
for (i = 0; i < POOL_SIZE; i++) {
p[i] = alloc_get(mem, POOL_SIZE, 1, 1);
for (i = 0; i < pool_size; i++) {
p[i] = alloc_get(mem, pool_size, 1, 1);
if (!p[i])
break;
}
......@@ -100,13 +99,13 @@ int main(int argc, char *argv[])
/* Uncomment this for a more intuitive view of what the
* allocator looks like after all these 1 byte allocs. */
#if 0
alloc_visualize(stderr, mem, POOL_SIZE);
alloc_visualize(stderr, mem, pool_size);
#endif
num = i;
/* Can't allocate this many. */
ok1(num != POOL_SIZE);
ok1(alloc_check(mem, POOL_SIZE));
ok1(num != pool_size);
ok1(alloc_check(mem, pool_size));
/* Sort them. */
sort(p, num, addr_cmp);
......@@ -114,55 +113,66 @@ int main(int argc, char *argv[])
/* Uniqueness check */
ok1(unique(p, num));
ok1(free_every_second_one(mem, num, p));
ok1(alloc_check(mem, POOL_SIZE));
ok1(free_every_second_one(mem, num, pool_size, p));
ok1(alloc_check(mem, pool_size));
/* Should be able to reallocate max size. */
p[0] = alloc_get(mem, POOL_SIZE, max_size, 1);
p[0] = alloc_get(mem, pool_size, max_size, 1);
ok1(p[0]);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, POOL_SIZE, p[0]) >= max_size);
ok1(alloc_check(mem, pool_size));
ok1(alloc_size(mem, pool_size, p[0]) >= max_size);
/* Re-initializing should be the same as freeing everything */
alloc_init(mem, POOL_SIZE);
ok1(alloc_check(mem, POOL_SIZE));
p[0] = alloc_get(mem, POOL_SIZE, max_size, 1);
alloc_init(mem, pool_size);
ok1(alloc_check(mem, pool_size));
p[0] = alloc_get(mem, pool_size, max_size, 1);
ok1(p[0]);
ok1(alloc_size(mem, POOL_SIZE, p[0]) >= max_size);
ok1(alloc_check(mem, POOL_SIZE));
alloc_free(mem, POOL_SIZE, p[0]);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, pool_size, p[0]) >= max_size);
ok1(alloc_check(mem, pool_size));
alloc_free(mem, pool_size, p[0]);
ok1(alloc_check(mem, pool_size));
/* Alignment constraints should be met, as long as powers of two */
for (i = 0; i < /*FIXME: POOL_ORD-1*/ 10; i++) {
p[i] = alloc_get(mem, POOL_SIZE, i, 1 << i);
for (i = 0; (1 << i) < alloc_limit; i++) {
p[i] = alloc_get(mem, pool_size, i, 1 << i);
ok1(p[i]);
ok1(((unsigned long)p[i] % (1 << i)) == 0);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, POOL_SIZE, p[i]) >= i);
ok1(alloc_check(mem, pool_size));
ok1(alloc_size(mem, pool_size, p[i]) >= i);
}
for (i = 0; i < /*FIXME: POOL_ORD-1*/ 10; i++) {
alloc_free(mem, POOL_SIZE, p[i]);
ok1(alloc_check(mem, POOL_SIZE));
for (i = 0; (1 << i) < alloc_limit; i++) {
alloc_free(mem, pool_size, p[i]);
ok1(alloc_check(mem, pool_size));
}
/* Alignment constraints for a single-byte allocation. */
for (i = 0; i < /*FIXME: POOL_ORD*/ 10; i++) {
p[0] = alloc_get(mem, POOL_SIZE, 1, 1 << i);
for (i = 0; (1 << i) < alloc_limit; i++) {
p[0] = alloc_get(mem, pool_size, 1, 1 << i);
ok1(p[0]);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, POOL_SIZE, p[i]) >= 1);
alloc_free(mem, POOL_SIZE, p[0]);
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_check(mem, pool_size));
ok1(alloc_size(mem, pool_size, p[i]) >= 1);
alloc_free(mem, pool_size, p[0]);
ok1(alloc_check(mem, pool_size));
}
/* Alignment check for a 0-byte allocation. Corner case. */
p[0] = alloc_get(mem, POOL_SIZE, 0, 1 << (/*FIXME: POOL_ORD - 1*/ 10));
ok1(alloc_check(mem, POOL_SIZE));
ok1(alloc_size(mem, POOL_SIZE, p[0]) < POOL_SIZE);
alloc_free(mem, POOL_SIZE, p[0]);
ok1(alloc_check(mem, POOL_SIZE));
p[0] = alloc_get(mem, pool_size, 0, alloc_limit);
ok1(alloc_check(mem, pool_size));
ok1(alloc_size(mem, pool_size, p[0]) < pool_size);
alloc_free(mem, pool_size, p[0]);
ok1(alloc_check(mem, pool_size));
}
int main(int argc, char *argv[])
{
plan_tests(112 + 92);
/* Large test. */
test(MIN_USEFUL_SIZE * 2);
/* Small test. */
test(MIN_USEFUL_SIZE / 2);
return exit_status();
}
ccan/alloc/tiny.c 0 → 100755
View file @ 7f9d9565
#include "tiny.h"
#include "bitops.h"
#include <assert.h>
#include <stdlib.h>
#include <string.h>
/* One byte header, one byte data. */
#define MIN_BLOCK_SIZE 2
/* Bit 7 (in any byte) == start or end. */
#define TERM_BIT 0x80
/* Bit 6 (first and last byte) == one byte long. */
#define SINGLE_BYTE 0x40
/* Bit 5 (of first byte) == "is this block free?" */
#define FREE_BIT 0x20
/* Val is usually offset by MIN_BLOCK_SIZE here. */
static unsigned encode_length(unsigned long val)
{
unsigned int bits = fls(val);
/* 5 bits in first byte. */
if (bits <= 5)
return 1;
/* 6 bits in last byte, 7 bits in middle ones. */
return 2 + (bits - 5) / 7;
}
/* Header is included in length, so we might need an extra byte. */
static unsigned encode_len_with_header(unsigned long len)
{
unsigned int hdrlen = 1;
assert(len);
while (encode_length(len + hdrlen - MIN_BLOCK_SIZE) != hdrlen)
hdrlen = encode_length(len + hdrlen - MIN_BLOCK_SIZE);
return hdrlen;
}
/* Encoding can be read from front or back; 0 is invalid at either
* start or end. Returns bytes used for header, or 0 if won't fit. */
static unsigned encode(unsigned long len, bool free, unsigned char arr[],
size_t limit)
{
unsigned int hdrlen = 1;
/* We can never have a length < MIN_BLOCK_SIZE. */
assert(len >= MIN_BLOCK_SIZE);
len -= MIN_BLOCK_SIZE;
if (encode_length(len) > limit)
return 0;
/* First byte always contains free bit. */
arr[0] = TERM_BIT | (free ? FREE_BIT : 0);
/* Also holds 5 bits of data (0 - 31) */
arr[0] |= (len & 0x1F);
len >>= 5;
/* One byte only? */
if (!len) {
arr[0] |= SINGLE_BYTE;
return hdrlen;
}
/* Middle bytes. */
while (len >= (1 << 6)) {
/* Next 7 data bits */
arr[hdrlen++] = (len & 0x7F);
len >>= 7;
}
arr[hdrlen++] = (len | TERM_BIT);
return hdrlen;
}
/* Returns bytes used for header. */
static unsigned decode(unsigned long *len, bool *free, const unsigned char *arr)
{
unsigned int hdrlen = 0, bits = 5;
/* Free flag is in bit 5 */
*free = (arr[hdrlen] & FREE_BIT);
/* Bottom five bits are data. */
*len = (arr[hdrlen] & 0x1f);
if (!(arr[hdrlen++] & SINGLE_BYTE)) {
/* Multi-byte encoding? */
while (!(arr[hdrlen] & TERM_BIT)) {
/* 7 more data bits. */
*len |= (arr[hdrlen] & 0x7fUL) << bits;
hdrlen++;
bits += 7;
}
/* Final byte has 6 bits. */
*len |= (arr[hdrlen] & 0x3fUL) << bits;
hdrlen++;
}
*len += MIN_BLOCK_SIZE;
return hdrlen;
}
/* We keep a recently-freed array, one byte per k. */
static unsigned long free_array_size(unsigned long poolsize)
{
return poolsize / 1024;
}
void tiny_alloc_init(void *pool, unsigned long poolsize)
{
/* We start with free array, and then the rest is free. */
unsigned long arrsize = free_array_size(poolsize);
/* Do nothing with 1 byte or less! */
if (poolsize < MIN_BLOCK_SIZE)
return;
memset(pool, 0, arrsize);
encode(poolsize - arrsize, true,
(unsigned char *)pool + arrsize, poolsize - arrsize);
}
/* Walk through and try to coalesce */
static bool try_coalesce(unsigned char *pool, unsigned long poolsize)
{
unsigned long len, hdrlen, prev_off = 0, prev_len = 0, off;
bool free, prev_free = false, coalesced = false;
off = free_array_size(poolsize);
do {
hdrlen = decode(&len, &free, pool + off);
if (free && prev_free) {
encode(prev_len + len, true, pool + prev_off,
poolsize - prev_off);
coalesced = true;
}
prev_free = free;
prev_off = off;
prev_len = len;
off += len;
} while (off < poolsize);
return coalesced;
}
static bool long_enough(unsigned long offset, unsigned long len,
unsigned long size, unsigned long align)
{
unsigned long end = offset + len;
offset += encode_len_with_header(len);
offset = align_up(offset, align);
return offset + size <= end;
}
void *tiny_alloc_get(void *pool, unsigned long poolsize,
unsigned long size, unsigned long align)
{
unsigned long arrsize = free_array_size(poolsize);
unsigned long len, off, actual, hdr, hdrlen;
bool free;
/* We can't do anything with tiny pools. */
if (poolsize < MIN_BLOCK_SIZE)
return NULL;
/* We don't do zero-allocs; allows 1 more offset in encoding. */
if (!size)
size = 1;
/* FIXME: Look through free array. */
again:
off = arrsize;
hdrlen = decode(&len, &free, (unsigned char *)pool + off);
while (!free || !long_enough(off, len, size, align)) {
/* FIXME: Refill free array if this block is free. */
/* Hit end? */
off += len;
if (off == poolsize) {
if (try_coalesce(pool, poolsize))
goto again;
return NULL;
}
hdrlen = decode(&len, &free, (unsigned char *)pool + off);
}
/* We have a free block. Since we walk from front, take far end. */
actual = ((off + len - size) & ~(align - 1));
hdr = actual - encode_len_with_header(off + len - actual);
/* Do we have enough room to split? */
if (hdr - off >= MIN_BLOCK_SIZE) {
encode(hdr - off, true, (unsigned char *)pool + off, poolsize);
} else {
hdr = off;
}
/* Make sure that we are all-zero up to actual, so we can walk back
* and find header. */
memset((unsigned char *)pool + hdr, 0, actual - hdr);
/* Create header for allocated block. */
encode(off + len - hdr, false, (unsigned char *)pool + hdr, poolsize);
return (unsigned char *)pool + actual;
}
static unsigned char *to_hdr(void *p)
{
unsigned char *hdr = p;
/* Walk back to find end of header. */
while (!*(--hdr));
assert(*hdr & TERM_BIT);
/* Now walk back to find start of header. */
if (!(*hdr & SINGLE_BYTE)) {
while (!(*(--hdr) & TERM_BIT));
}
return hdr;
}
void tiny_alloc_free(void *pool, unsigned long poolsize, void *freep)
{
unsigned char *hdr;
/* Too small to do anything. */
if (poolsize < MIN_BLOCK_SIZE)
return;
hdr = to_hdr(freep);
/* FIXME: Put in free array. */
hdr[0] |= FREE_BIT;
}
unsigned long tiny_alloc_size(void *pool, unsigned long poolsize, void *p)
{
unsigned char *hdr = to_hdr(p);
unsigned long len, hdrlen;
bool free;
hdrlen = decode(&len, &free, hdr);
return len - hdrlen;
}
/* Useful for gdb breakpoints. */
static bool tiny_check_fail(void)
{
return false;
}
bool tiny_alloc_check(void *pool, unsigned long poolsize)
{
unsigned long arrsize = free_array_size(poolsize);
unsigned char *arr = pool;
unsigned long len, off, hdrlen;
bool free;
if (poolsize < MIN_BLOCK_SIZE)
return true;
/* For the moment, free array is all zeroes. */
for (off = 0; off < arrsize; off++) {
if (arr[off] != 0)
return tiny_check_fail();
}
for (off = arrsize; off < poolsize; off += len) {
/* We should have a valid header. */
if (!(arr[off] & TERM_BIT))
return tiny_check_fail();
if (!(arr[off] & SINGLE_BYTE)) {
unsigned long off2;
for (off2 = off+1; off2 < poolsize; off2++) {
if (arr[off2] & TERM_BIT)
break;
}
if (off2 == poolsize)
return tiny_check_fail();
}
hdrlen = decode(&len, &free, arr + off);
if (off + len > poolsize)
return tiny_check_fail();
if (hdrlen != encode_length(len - MIN_BLOCK_SIZE))
return tiny_check_fail();
}
return true;
}
/* FIXME: Implement. */
void tiny_alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
{
}
ccan/alloc/tiny.h 0 → 100644
View file @ 7f9d9565
#ifndef CCAN_TINY_H
#define CCAN_TINY_H
#include <stdbool.h>
#include <stdio.h>
void tiny_alloc_init(void *pool, unsigned long poolsize);
void *tiny_alloc_get(void *pool, unsigned long poolsize,
unsigned long size, unsigned long align);
void tiny_alloc_free(void *pool, unsigned long poolsize, void *free);
unsigned long tiny_alloc_size(void *pool, unsigned long poolsize, void *p);
bool tiny_alloc_check(void *pool, unsigned long poolsize);
void tiny_alloc_visualize(FILE *out, void *pool, unsigned long poolsize);
#endif /* CCAN_TINY_H */
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