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bionic: revert to a single (larger) property area
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d329697 is too complicated.  Change the multiple property pages back to
a single 128K property area that's mapped in entirely at initialization
(the memory will not get allocated until the pages are touched).

d329697 has other changes useful for testing (moving property area
initialization inside bionic and adding __system_property_set_filename)
so undo the change manually rather than with git revert.

Signed-off-by: Greg Hackmann <[email protected]>

(cherry picked from commit 5f05348)

Change-Id: I690704552afc07a4dd410277893ca9c40bc13e5f
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@greghackmann @colincross
greghackmann authored and colincross committed Jun 24, 2013
1 parent 996cdc4 commit 1540f60
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Showing 4 changed files with 36 additions and 89 deletions.
91 changes: 25 additions & 66 deletions libc/bionic/system_properties.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,7 @@ typedef struct prop_bt prop_bt;
static const char property_service_socket[] = "/dev/socket/" PROP_SERVICE_NAME;
static char property_filename[PATH_MAX] = PROP_FILENAME;

prop_area *__system_property_regions__[PA_REGION_COUNT] = { NULL, };
prop_area *__system_property_area__ = NULL;

const size_t PA_DATA_SIZE = PA_SIZE - sizeof(prop_area);

Expand All @@ -124,15 +124,10 @@ static int get_fd_from_env(void)
return atoi(env);
}

static int map_prop_region_rw(size_t region)
static int map_prop_area_rw()
{
prop_area *pa;
int fd;
size_t offset = region * PA_SIZE;

if (__system_property_regions__[region]) {
return 0;
}

/* dev is a tmpfs that we can use to carve a shared workspace
* out of, so let's do that...
Expand All @@ -148,24 +143,21 @@ static int map_prop_region_rw(size_t region)
return -1;
}

if (ftruncate(fd, offset + PA_SIZE) < 0)
if (ftruncate(fd, PA_SIZE) < 0)
goto out;

pa = mmap(NULL, PA_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset);
pa = mmap(NULL, PA_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if(pa == MAP_FAILED)
goto out;

memset(pa, 0, PA_SIZE);
pa->magic = PROP_AREA_MAGIC;
pa->version = PROP_AREA_VERSION;

if (!region) {
/* reserve root node */
pa->bytes_used += sizeof(prop_bt);
}
/* reserve root node */
pa->bytes_used = sizeof(prop_bt);

/* plug into the lib property services */
__system_property_regions__[region] = pa;
__system_property_area__ = pa;

close(fd);
return 0;
Expand All @@ -187,20 +179,14 @@ int __system_property_set_filename(const char *filename)

int __system_property_area_init()
{
return map_prop_region_rw(0);
return map_prop_area_rw();
}

static int map_prop_region(size_t region)
static int map_prop_area()
{
bool fromFile = true;
bool swapped;
size_t offset = region * PA_SIZE;
int result = -1;

if(__system_property_regions__[region]) {
return 0;
}

int fd = open(property_filename, O_RDONLY | O_NOFOLLOW);

if ((fd < 0) && (errno == ENOENT)) {
Expand Down Expand Up @@ -229,11 +215,11 @@ static int map_prop_region(size_t region)
if ((fd_stat.st_uid != 0)
|| (fd_stat.st_gid != 0)
|| ((fd_stat.st_mode & (S_IWGRP | S_IWOTH)) != 0)
|| (fd_stat.st_size < offset + PA_SIZE) ) {
|| (fd_stat.st_size < PA_SIZE) ) {
goto cleanup;
}

prop_area *pa = mmap(NULL, PA_SIZE, PROT_READ, MAP_SHARED, fd, offset);
prop_area *pa = mmap(NULL, PA_SIZE, PROT_READ, MAP_SHARED, fd, 0);

if (pa == MAP_FAILED) {
goto cleanup;
Expand All @@ -245,16 +231,8 @@ static int map_prop_region(size_t region)
}

result = 0;
swapped = __sync_bool_compare_and_swap(&__system_property_regions__[region],
NULL, pa);
if (!swapped) {
/**
* In the event of a race either mapping is equally good, so
* the thread that lost can just throw its mapping away and proceed as
* normal.
*/
munmap(pa, PA_SIZE);
}

__system_property_area__ = pa;

cleanup:
if (fromFile) {
Expand All @@ -266,33 +244,20 @@ static int map_prop_region(size_t region)

int __system_properties_init()
{
return map_prop_region(0);
return map_prop_area();
}

static void *new_prop_obj(size_t size, prop_off_t *off)
{
prop_area *pa;
size_t i, idx;
prop_area *pa = __system_property_area__;
size = ALIGN(size, sizeof(uint32_t));

for (i = 0; i < PA_REGION_COUNT; i++) {
int err = map_prop_region_rw(i);
if (err < 0) {
return NULL;
}

pa = __system_property_regions__[i];
if (pa->bytes_used + size <= PA_DATA_SIZE)
break;
}

if (i == PA_REGION_COUNT)
if (pa->bytes_used + size > PA_DATA_SIZE)
return NULL;

idx = pa->bytes_used;
*off = idx + i * PA_DATA_SIZE;
pa->bytes_used += size;
return pa->data + idx;
*off = pa->bytes_used;
__system_property_area__->bytes_used += size;
return __system_property_area__->data + *off;
}

static prop_bt *new_prop_bt(const char *name, uint8_t namelen, prop_off_t *off)
Expand Down Expand Up @@ -330,16 +295,10 @@ static prop_info *new_prop_info(const char *name, uint8_t namelen,

static void *to_prop_obj(prop_off_t off)
{
size_t region = off / PA_DATA_SIZE;
size_t idx = off % PA_DATA_SIZE;

if (region > PA_REGION_COUNT)
return NULL;

if (map_prop_region(region) < 0)
if (off > PA_DATA_SIZE)
return NULL;

return __system_property_regions__[region]->data + idx;
return __system_property_area__->data + off;
}

static prop_bt *root_node()
Expand Down Expand Up @@ -570,7 +529,7 @@ int __system_property_wait(const prop_info *pi)
{
unsigned n;
if(pi == 0) {
prop_area *pa = __system_property_regions__[0];
prop_area *pa = __system_property_area__;
n = pa->serial;
do {
__futex_wait(&pa->serial, n, 0);
Expand All @@ -586,7 +545,7 @@ int __system_property_wait(const prop_info *pi)

int __system_property_update(prop_info *pi, const char *value, unsigned int len)
{
prop_area *pa = __system_property_regions__[0];
prop_area *pa = __system_property_area__;

if (len >= PROP_VALUE_MAX)
return -1;
Expand All @@ -607,7 +566,7 @@ int __system_property_update(prop_info *pi, const char *value, unsigned int len)
int __system_property_add(const char *name, unsigned int namelen,
const char *value, unsigned int valuelen)
{
prop_area *pa = __system_property_regions__[0];
prop_area *pa = __system_property_area__;
const prop_info *pi;

if (namelen >= PROP_NAME_MAX)
Expand All @@ -633,7 +592,7 @@ unsigned int __system_property_serial(const prop_info *pi)

unsigned int __system_property_wait_any(unsigned int serial)
{
prop_area *pa = __system_property_regions__[0];
prop_area *pa = __system_property_area__;

do {
__futex_wait(&pa->serial, serial, 0);
Expand Down
6 changes: 1 addition & 5 deletions libc/include/sys/_system_properties.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,11 +42,7 @@ typedef struct prop_msg prop_msg;
#define PROP_SERVICE_NAME "property_service"
#define PROP_FILENAME "/dev/__properties__"

/* (4 header words + 28 toc words) = 128 bytes */
/* 128 bytes header and toc + 28 prop_infos @ 128 bytes = 3712 bytes */

#define PA_REGION_COUNT 128
#define PA_SIZE 4096
#define PA_SIZE (128 * 1024)

#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
#define SERIAL_DIRTY(serial) ((serial) & 1)
Expand Down
14 changes: 5 additions & 9 deletions tests/property_benchmark.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@
#include <vector>
#include <string>

extern void *__system_property_regions__[PA_REGION_COUNT];
extern void *__system_property_area__;

#define TEST_NUM_PROPS \
Arg(1)->Arg(4)->Arg(16)->Arg(64)->Arg(128)->Arg(256)->Arg(512)->Arg(1024)
Expand All @@ -39,10 +39,8 @@ struct LocalPropertyTestState {
return;
}

for (size_t i = 0; i < PA_REGION_COUNT; i++) {
old_pa[i] = __system_property_regions__[i];
__system_property_regions__[i] = NULL;
}
old_pa = __system_property_area__;
__system_property_area__ = NULL;

pa_dirname = dirname;
pa_filename = pa_dirname + "/__properties__";
Expand Down Expand Up @@ -79,9 +77,7 @@ struct LocalPropertyTestState {
if (!valid)
return;

for (size_t i = 0; i < PA_REGION_COUNT; i++) {
__system_property_regions__[i] = old_pa[i];
}
__system_property_area__ = old_pa;

__system_property_set_filename(PROP_FILENAME);
unlink(pa_filename.c_str());
Expand All @@ -107,7 +103,7 @@ struct LocalPropertyTestState {
private:
std::string pa_dirname;
std::string pa_filename;
void *old_pa[PA_REGION_COUNT];
void *old_pa;
};

static void BM_property_get(int iters, int nprops)
Expand Down
14 changes: 5 additions & 9 deletions tests/system_properties_test.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>

extern void *__system_property_regions__[PA_REGION_COUNT];
extern void *__system_property_area__;

struct LocalPropertyTestState {
LocalPropertyTestState() : valid(false) {
Expand All @@ -35,10 +35,8 @@ struct LocalPropertyTestState {
return;
}

for (size_t i = 0; i < PA_REGION_COUNT; i++) {
old_pa[i] = __system_property_regions__[i];
__system_property_regions__[i] = NULL;
}
old_pa = __system_property_area__;
__system_property_area__ = NULL;

pa_dirname = dirname;
pa_filename = pa_dirname + "/__properties__";
Expand All @@ -52,9 +50,7 @@ struct LocalPropertyTestState {
if (!valid)
return;

for (size_t i = 0; i < PA_REGION_COUNT; i++) {
__system_property_regions__[i] = old_pa[i];
}
__system_property_area__ = old_pa;

__system_property_set_filename(PROP_FILENAME);
unlink(pa_filename.c_str());
Expand All @@ -65,7 +61,7 @@ struct LocalPropertyTestState {
private:
std::string pa_dirname;
std::string pa_filename;
void *old_pa[PA_REGION_COUNT];
void *old_pa;
};

TEST(properties, add) {
Expand Down

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