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Fix GC bug which did not increment the proper variable.
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Fix warning regarding the initial hash value.
Use php_uint32 everywhere.
Speedup linked-list traversal by using the hash value.
Degrade linked-list to singledly linked-list.
Allocate a new shared memory buffer, if the data does not fit into the
current one.  Prior to this change, we always allocated a new buffer.
Fix debug prints to be compatible with non-GCC compilers.
NUL-terminate string return values.
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Sascha Schumann committed Jul 18, 2001
1 parent 9638928 commit 664df24
Showing 1 changed file with 73 additions and 61 deletions.
134 changes: 73 additions & 61 deletions ext/session/mod_mm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,16 +33,21 @@

#define PS_MM_PATH "/tmp/session_mm"

/* For php_uint32 */
#include "ext/standard/basic_functions.h"

/*
* this list holds all data associated with one session
*/

typedef struct ps_sd {
struct ps_sd *next, *prev;
time_t ctime;
struct ps_sd *next;
php_uint32 hv; /* hash value of key */
time_t ctime; /* time of last change */
char *key;
void *data;
size_t datalen;
size_t datalen; /* amount of valid data */
size_t alloclen; /* amount of allocated memory for data */
} ps_sd;

typedef struct {
Expand All @@ -56,20 +61,17 @@ static ps_mm *ps_mm_instance = NULL;
#define HASH_SIZE 577

#if 0
#define ps_mm_debug(a...) fprintf(stderr, a)
#define ps_mm_debug(a) printf a
#else
#define ps_mm_debug
#define ps_mm_debug(a)
#endif

/* For php_uint32 */
#include "ext/standard/basic_functions.h"

static php_uint32 ps_sd_hash(const char *data)
static inline php_uint32 ps_sd_hash(const char *data)
{
php_uint32 h;
char c;

for (h = 2166136261; (c = *data++); ) {
for (h = 2166136261U; (c = *data++); ) {
h *= 16777619;
h ^= c;
}
Expand All @@ -80,23 +82,25 @@ static php_uint32 ps_sd_hash(const char *data)

static ps_sd *ps_sd_new(ps_mm *data, const char *key, const void *sdata, size_t sdatalen)
{
php_uint32 h;
php_uint32 hv, slot;
ps_sd *sd;

h = ps_sd_hash(key) % HASH_SIZE;
hv = ps_sd_hash(key);
slot = hv % HASH_SIZE;

sd = mm_malloc(data->mm, sizeof(*sd));
if (!sd)
return NULL;
sd->ctime = 0;
sd->hv = hv;

sd->data = mm_malloc(data->mm, sdatalen);
if (!sd->data) {
mm_free(data->mm, sd);
return NULL;
}

sd->datalen = sdatalen;
sd->alloclen = sd->datalen = sdatalen;

sd->key = mm_strdup(data->mm, key);
if (!sd->key) {
Expand All @@ -107,30 +111,29 @@ static ps_sd *ps_sd_new(ps_mm *data, const char *key, const void *sdata, size_t

memcpy(sd->data, sdata, sdatalen);

if ((sd->next = data->hash[h]))
sd->next->prev = sd;
sd->prev = NULL;

ps_mm_debug("inserting %s(%p) into %d\n", key, sd, h);
sd->next = data->hash[slot];
data->hash[slot] = sd;

data->hash[h] = sd;
ps_mm_debug(("inserting %s(%p) into slot %d\n", key, sd, slot));

return sd;
}

static void ps_sd_destroy(ps_mm *data, ps_sd *sd)
{
unsigned int h;
php_uint32 slot;

h = ps_sd_hash(sd->key) % HASH_SIZE;

if (sd->next)
sd->next->prev = sd->prev;
if (sd->prev)
sd->prev->next = sd->next;

if (data->hash[h] == sd)
data->hash[h] = sd->next;
slot = ps_sd_hash(sd->key) % HASH_SIZE;

if (data->hash[slot] == sd)
data->hash[slot] = sd->next;
else {
ps_sd *prev;

/* There must be some entry before the one we want to delete */
for (prev = data->hash[slot]; prev->next != sd; prev = prev->next);
prev->next = sd->next;
}

mm_free(data->mm, sd->key);
if (sd->data)
Expand All @@ -140,23 +143,24 @@ static void ps_sd_destroy(ps_mm *data, ps_sd *sd)

static ps_sd *ps_sd_lookup(ps_mm *data, const char *key, int rw)
{
unsigned int h;
php_uint32 hv, slot;
ps_sd *ret;

h = ps_sd_hash(key) % HASH_SIZE;

for (ret = data->hash[h]; ret; ret = ret->next)
if (!strcmp(ret->key, key))
hv = ps_sd_hash(key);
slot = hv % HASH_SIZE;

for (ret = data->hash[slot]; ret; ret = ret->next)
if (ret->hv == hv && !strcmp(ret->key, key))
break;

if (ret && rw && ret != data->hash[h]) {
data->hash[h]->prev = ret;
ret->next = data->hash[h];
data->hash[h] = ret;
ps_mm_debug("optimizing\n");
if (ret && rw && ret != data->hash[slot]) {
/* Move the entry to the top of the linked list */

ret->next = data->hash[slot];
data->hash[slot] = ret;
}

ps_mm_debug("lookup(%s): ret=%p,h=%d\n", key, ret, h);
ps_mm_debug(("lookup(%s): ret=%p,hv=%u,slot=%d\n", key, ret, hv, slot));

return ret;
}
Expand Down Expand Up @@ -221,7 +225,7 @@ PHP_MSHUTDOWN_FUNCTION(ps_mm)

PS_OPEN_FUNC(mm)
{
ps_mm_debug("open: ps_mm_instance=%p\n", ps_mm_instance);
ps_mm_debug(("open: ps_mm_instance=%p\n", ps_mm_instance));

if (!ps_mm_instance)
return FAILURE;
Expand Down Expand Up @@ -249,8 +253,9 @@ PS_READ_FUNC(mm)
sd = ps_sd_lookup(data, key, 0);
if (sd) {
*vallen = sd->datalen;
*val = emalloc(sd->datalen);
*val = emalloc(sd->datalen + 1);
memcpy(*val, sd->data, sd->datalen);
(*val)[sd->datalen] = '\0';
ret = SUCCESS;
}

Expand All @@ -264,24 +269,29 @@ PS_WRITE_FUNC(mm)
PS_MM_DATA;
ps_sd *sd;

if (vallen == 0) return SUCCESS;

mm_lock(data->mm, MM_LOCK_RW);

sd = ps_sd_lookup(data, key, 1);
if (!sd) {
sd = ps_sd_new(data, key, val, vallen);
ps_mm_debug("new one for %s\n", key);
ps_mm_debug(("new entry for %s\n", key));
} else {
ps_mm_debug("found existing one for %s\n", key);
mm_free(data->mm, sd->data);
sd->datalen = vallen;
sd->data = mm_malloc(data->mm, vallen);
if (!sd->data) {
ps_sd_destroy(data, sd);
sd = NULL;
} else
ps_mm_debug(("found existing entry for %s\n", key));

if (vallen >= sd->alloclen) {
mm_free(data->mm, sd->data);
sd->alloclen = vallen + 1;
sd->data = mm_malloc(data->mm, sd->alloclen);

if (!sd->data) {
ps_sd_destroy(data, sd);
sd = NULL;
}
}
if (sd) {
sd->datalen = vallen;
memcpy(sd->data, val, vallen);
}
}

if (sd)
Expand Down Expand Up @@ -312,23 +322,25 @@ PS_GC_FUNC(mm)
{
PS_MM_DATA;
int h;
time_t now;
time_t limit;
ps_sd *sd, *next;

*nrdels = 0;
ps_mm_debug("gc\n");

ps_mm_debug(("gc\n"));

time(&limit);

limit -= maxlifetime;

mm_lock(data->mm, MM_LOCK_RW);

time(&now);

for (h = 0; h < HASH_SIZE; h++)
for (sd = data->hash[h]; sd; sd = next) {
next = sd->next;
ps_mm_debug("looking at %s\n", sd->key);
if ((now - sd->ctime) > maxlifetime) {
if (sd->ctime < limit) {
ps_mm_debug(("purging %s\n", sd->key));
ps_sd_destroy(data, sd);
*nrdels++;
(*nrdels)++;
}
}

Expand Down

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