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⚡ Performance: Use Read-Write Lock for Path Resolution #195

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⚡ Performance: Use Read-Write Lock for Path Resolution #195

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53 changes: 33 additions & 20 deletions src/link.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
* \details This allows LinkTable generation to be run exclusively. This
* effectively gives LinkTable generation priority over file transfer.
*/
static pthread_mutex_t link_lock;
static pthread_rwlock_t link_lock;
static void make_link_relative(const char *page_url, char *link_url);

/**
Expand Down Expand Up @@ -286,7 +286,7 @@

LinkTable *LinkSystem_init(const char *url)
{
PTHREAD_MUTEX_INIT(&link_lock, NULL);
pthread_rwlock_init(&link_lock, NULL);
int url_len = strnlen(url, MAX_PATH_LEN) - 1;
/*
* --------- Set the length of the root link -----------
Expand Down Expand Up @@ -845,93 +845,106 @@
return next_table;
}

static Link *path_to_Link_recursive(char *path, LinkTable *linktbl)
{
/*
* skip the leading '/' if it exists
*/
if (*path == '/') {
path++;
}

/*
* remove the last '/' if it exists
*/
char *slash = &(path[strnlen(path, MAX_PATH_LEN) - 1]);
if (*slash == '/') {
*slash = '\0';
}

slash = strchr(path, '/');
if (slash == NULL) {
/*
* We cannot find another '/', we have reached the last level
*/
for (int i = 1; i < linktbl->num; i++) {
if (!strncmp
(path, linktbl->links[i]->linkname, MAX_FILENAME_LEN)) {
/*
* We found our link
*/
return linktbl->links[i];
}
}
} else {
/*
* We can still find '/', time to consume the path and traverse
* the tree structure
*/

/*
* add termination mark to the current string,
* effective create two substrings
*/
*slash = '\0';
/*
* move the pointer past the '/'
*/
char *next_path = slash + 1;
for (int i = 1; i < linktbl->num; i++) {
if (!strncmp
(path, linktbl->links[i]->linkname, MAX_FILENAME_LEN)) {
/*
* The next sub-directory exists
*/
LinkTable *next_table = linktbl->links[i]->next_table;
if (!next_table) {
if (CONFIG.mode == NORMAL) {
next_table =
LinkTable_new(linktbl->links[i]->f_url);
} else if (CONFIG.mode == SONIC) {
if (!CONFIG.sonic_id3) {
pthread_rwlock_unlock(&link_lock);
pthread_rwlock_wrlock(&link_lock);
next_table = linktbl->links[i]->next_table;

if (!next_table) {
if (CONFIG.mode == NORMAL) {
next_table =
sonic_LinkTable_new_index
(linktbl->links[i]->sonic.id);
LinkTable_new(linktbl->links[i]->f_url);
} else if (CONFIG.mode == SONIC) {
if (!CONFIG.sonic_id3) {
next_table =
sonic_LinkTable_new_index
(linktbl->links[i]->sonic.id);
} else {
next_table =
sonic_LinkTable_new_id3
(linktbl->links
[i]->sonic.depth,
linktbl->links[i]->sonic.id);
}
} else {
next_table =
sonic_LinkTable_new_id3
(linktbl->links
[i]->sonic.depth,
linktbl->links[i]->sonic.id);
lprintf(fatal, "Invalid CONFIG.mode\n");
}
} else {
lprintf(fatal, "Invalid CONFIG.mode\n");
linktbl->links[i]->next_table = next_table;
}
pthread_rwlock_unlock(&link_lock);
pthread_rwlock_rdlock(&link_lock);
next_table = linktbl->links[i]->next_table;
}
if (next_table) {
return path_to_Link_recursive(next_path, next_table);
} else {
return NULL;
}
linktbl->links[i]->next_table = next_table;
return path_to_Link_recursive(next_path, next_table);
}
}
}
return NULL;
}

Check notice on line 941 in src/link.c

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codefactor.io / CodeFactor

src/link.c#L848-L941 

Complex Method
Link *path_to_Link(const char *path)
{
lprintf(link_lock_debug,
"thread %x: locking link_lock;\n", pthread_self());

PTHREAD_MUTEX_LOCK(&link_lock);
pthread_rwlock_rdlock(&link_lock);
char *new_path = strndup(path, MAX_PATH_LEN);
if (!new_path) {
lprintf(fatal, "cannot allocate memory\n");
Expand All @@ -941,7 +954,7 @@

lprintf(link_lock_debug,
"thread %x: unlocking link_lock;\n", pthread_self());
PTHREAD_MUTEX_UNLOCK(&link_lock);
pthread_rwlock_unlock(&link_lock);
return link;
}

Expand Down
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