Add stringring implementation

[blerg.git] / common / stringring.c

diff --git a/common/stringring.c b/common/stringring.c
new file mode 100644 (file)
index 0000000..c788db8
--- /dev/null
+++ b/common/stringring.c
@@ -0,0 +1,174 @@
+/* Blerg is (C) 2011 The Dominion of Awesome, and is distributed under a
+ * BSD-style license.  Please see the COPYING file for details.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <stringring.h>
+
+#define STRINGRING_DATA_CHECK() \
+       if (sh == NULL)         \
+               return 0;       \
+       if (data == NULL)       \
+               return 0;       \
+       if (data[0] == 0)       \
+               return 0;
+
+
+struct stringring_handle * stringring_open(const char *filename) {
+       struct stringring_handle *sh;
+       struct stat st;
+       int initialize = 0;
+
+       sh = malloc(sizeof(struct stringring_handle));
+       if (sh == NULL) {
+               perror("stringring_handle malloc");
+               return NULL;
+       }
+
+       sh->fd = open(filename, O_RDWR | O_CREAT, 0600);
+       flock(sh->fd, LOCK_EX);
+       if (sh->fd == -1) {
+               perror("stringring open");
+               goto stringring_open__open_failed;
+       }
+
+       fstat(sh->fd, &st);
+       if (st.st_size < sizeof(struct stringring)) {
+               ftruncate(sh->fd, sizeof(struct stringring));
+               initialize = 1;
+       }
+       sh->sr = mmap(NULL, sizeof(struct stringring), PROT_READ | PROT_WRITE, MAP_SHARED, sh->fd, 0);
+       if (sh->sr == MAP_FAILED) {
+               perror("stringring mmap");
+               goto stringring_open__map_failed;
+       }
+
+       if (initialize) {
+               stringring_clear(sh);
+       }
+       flock(sh->fd, LOCK_UN);
+
+       return sh;
+
+stringring_open__map_failed:
+       flock(sh->fd, LOCK_UN);
+       fclose(sh->fd);
+stringring_open__open_failed:
+       free(sh);
+       return NULL;
+}
+
+void stringring_close(struct stringring_handle *sh) {
+       if (sh == NULL)
+               return;
+
+       if (sh->sr != NULL)
+               munmap(sh->sr, sizeof(struct stringring));
+
+       if (sh->fd > -1)
+               close(sh->fd);
+
+       free(sh);
+}
+
+int stringring_add(struct stringring_handle *sh, const char *data) {
+       STRINGRING_DATA_CHECK();
+
+       flock(sh->fd, LOCK_EX);
+       if (sh->sr->counter == 0) {
+               sh->sr->counter = STRINGRING_N_ENTRIES - 1;
+       } else {
+               sh->sr->counter--;
+       }
+
+       int data_len = strlen(data);
+       sh->sr->entries[sh->sr->counter].timestamp = time(NULL);
+       strncpy(sh->sr->entries[sh->sr->counter].data, data, STRINGRING_DATA_SIZE);
+       if (data_len < STRINGRING_DATA_SIZE) {
+               /* zero out the rest of the data */
+               memset(sh->sr->entries[sh->sr->counter].data + data_len, 0, STRINGRING_DATA_SIZE - data_len);
+       }
+       flock(sh->fd, LOCK_UN);
+
+       return 1;
+}
+
+int stringring_find_unlocked(struct stringring_handle *sh, const char *data, uint64_t cutoff) {
+       int n, i;
+
+       i = sh->sr->counter;
+       for (n = 0; n < STRINGRING_N_ENTRIES; n++) {
+               if (sh->sr->entries[i].timestamp > 0 &&
+                   sh->sr->entries[i].timestamp > cutoff &&
+                   strncmp(sh->sr->entries[i].data, data, STRINGRING_DATA_SIZE) == 0) {
+                       return i;
+               }
+               i = (i + 1) % STRINGRING_N_ENTRIES;
+       }
+
+       return -1;
+}
+
+int stringring_find(struct stringring_handle *sh, const char *data, unsigned int max_age) {
+       int ret;
+       uint64_t cutoff = (max_age > 0 ? time(NULL) - max_age : 0);
+
+       flock(sh->fd, LOCK_SH);
+       ret = stringring_find_unlocked(sh, data, cutoff);
+       flock(sh->fd, LOCK_UN);
+
+       return ret;
+}
+
+int stringring_remove_index_unlocked(struct stringring_handle *sh, int idx) {
+       if (sh == NULL)
+               return 0;
+       if (idx < 0 || idx >= STRINGRING_N_ENTRIES)
+               return 0;
+
+       sh->sr->entries[idx].timestamp = 0;
+       memset(sh->sr->entries[idx].data, 0, STRINGRING_DATA_SIZE);
+
+       return 1;
+}
+
+int stringring_remove_index(struct stringring_handle *sh, int idx) {
+       int ret;
+
+       flock(sh->fd, LOCK_EX);
+       ret = stringring_remove_index_unlocked(sh, idx);
+       flock(sh->fd, LOCK_UN);
+
+       return ret;
+}
+
+int stringring_remove(struct stringring_handle *sh, const char *data) {
+       STRINGRING_DATA_CHECK();
+       int ret;
+
+       flock(sh->fd, LOCK_EX);
+       ret = stringring_remove_index_unlocked(sh,
+                       stringring_find_unlocked(sh, data, 0));
+       flock(sh->fd, LOCK_UN);
+
+       return ret;
+}
+
+int stringring_clear(struct stringring_handle *sh) {
+       if (sh == NULL)
+               return 0;
+
+       flock(sh->fd, LOCK_EX);
+       memset(sh->sr, 0, sizeof(struct stringring));
+       flock(sh->fd, LOCK_UN);
+
+       return 1;
+}