lib: Shared Memory

Updated tests. Added code to drop a corner case (packet where the tail
PCI would cross the edge of the ring buffer) because solving this very
rare case is not worth the performance hit on the ringbuffer the extra
code would incur. This means the ringbuffer might drop a very small
percentage of packets.

1 files changed, 68 insertions, 134 deletions

diff --git a/src/lib/shm_du_map.c b/src/lib/shm_du_map.c
index d071b0c3..dc73077f 100644
--- a/src/lib/shm_du_map.c
+++ b/src/lib/shm_du_map.c
@@ -21,46 +21,33 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-#ifndef SHM_DU_MAP_C
-#define SHM_DU_MAP_C
-
 #include <ouroboros/shm_du_map.h>
-
 #include <pthread.h>
 #include <sys/mman.h>
 #include <fcntl.h>
 #include <malloc.h>
 #include <string.h>
 
-
-#define SHM_DU_BLOCK_DATA_SIZE (SHM_DU_BUFF_BLOCK_SIZE -                       \
-                                sizeof(struct shm_block))
-#define SHM_BLOCKS_IN_MAP (1 << SHM_DU_MAP_SIZE)
-#define SHM_BLOCKS_SIZE (SHM_DU_BUFF_BLOCK_SIZE * SHM_BLOCKS_IN_MAP)
-#define SHM_BUFFS_SIZE (SHM_BLOCKS_IN_MAP * sizeof (struct shm_du_buff))
-#define SHM_FILE_SIZE (SHM_BLOCKS_IN_MAP * (SHM_DU_BUFF_BLOCK_SIZE             \
-                                            + sizeof(struct shm_du_buff)       \
-                                            + sizeof(uint8_t))                 \
-                       + 2 * sizeof (size_t)                                   \
+#define SHM_BLOCKS_SIZE (SHM_BLOCKS_IN_MAP * SHM_DU_BUFF_BLOCK_SIZE)
+#define SHM_FILE_SIZE (SHM_BLOCKS_SIZE + 2 * sizeof (size_t)                   \
                        + sizeof(pthread_mutex_t))
 
-#define idx_to_block_ptr(dum, i) ((struct shm_block *)                         \
-                                  (dum->shm_base + i * SHM_DU_BUFF_BLOCK_SIZE))
-#define idx_to_du_buff_ptr(dum, i) (dum->ptr_du_buff + i)
-#define du_buff_ptr_to_idx(dum, sdb) ((sdb - dum->ptr_du_buff) / sizeof *sdb)
-#define block_ptr_to_idx(dum, sdb) (((uint8_t *)sdb - dum->shm_base)           \
-                                    / SHM_DU_BUFF_BLOCK_SIZE)
+#define get_head_ptr(dum)                                                      \
+((struct shm_du_buff *)(dum->shm_base + (*dum->ptr_head *                      \
+                                         SHM_DU_BUFF_BLOCK_SIZE)))
 
-#define shm_map_used(dum) ((*(dum->ptr_head) + SHM_BLOCKS_IN_MAP -             \
-                            *(dum->ptr_tail)) & (SHM_BLOCKS_IN_MAP - 1))
+#define get_tail_ptr(dum)                                                      \
+((struct shm_du_buff *)(dum->shm_base + (*dum->ptr_tail *                      \
+                                         SHM_DU_BUFF_BLOCK_SIZE)))
 
-#define shm_map_free(dum, i)(shm_map_used(dum) + i + 1 < SHM_BLOCKS_IN_MAP)
+#define block_ptr_to_idx(dum, sdb)                                             \
+        (((uint8_t *)sdb - dum->shm_base) / SHM_DU_BUFF_BLOCK_SIZE)
 
-struct shm_block {
-        size_t size;
-        long   next;
-        long   prev;
-};
+#define shm_map_used(dum)((*dum->ptr_head + SHM_BLOCKS_IN_MAP - *dum->ptr_tail)\
+                          & (SHM_BLOCKS_IN_MAP - 1))
+#define shm_map_free(dum, i)(shm_map_used(dum) + i < SHM_BLOCKS_IN_MAP)
+
+#define MIN(a,b)(a < b ? a : b)
 
 struct shm_du_buff {
         size_t            size;
@@ -70,7 +57,6 @@ struct shm_du_buff {
 
 struct shm_du_map {
         uint8_t            * shm_base;    /* start of blocks */
-        struct shm_du_buff * ptr_du_buff; /* start of du_buff structs */
         size_t             * ptr_head;    /* start of ringbuffer head */
         size_t             * ptr_tail;    /* start of ringbuffer tail */
         pthread_mutex_t    * shm_mutex;   /* lock all free space in shm */
@@ -86,25 +72,25 @@ struct shm_du_map * shm_du_map_create()
 
         dum = malloc(sizeof *dum);
         if (dum == NULL) {
-                LOG_ERR("Could not allocate struct.");
+                LOG_DBGF("Could not allocate struct.");
                 return NULL;
         }
 
         shm_fd = shm_open(SHM_DU_MAP_FILENAME, O_CREAT | O_EXCL | O_RDWR, 0666);
         if (shm_fd == -1) {
-                LOG_ERR("Failed creating shared memory map.");
+                LOG_DBGF("Failed creating shared memory map.");
                 free(dum);
                 return NULL;
         }
 
-        if (lseek (shm_fd,SHM_FILE_SIZE - 1, SEEK_SET) < 0) {
-                LOG_ERR("Failed to extend shared memory map.");
+        if (lseek(shm_fd, SHM_FILE_SIZE - 1, SEEK_SET) < 0) {
+                LOG_DBGF("Failed to extend shared memory map.");
                 free(dum);
                 return NULL;
         }
 
-        if (write (shm_fd, "", 1) != 1) {
-                LOG_ERR("Failed to finalise extension of shared memory map.");
+        if (write(shm_fd, "", 1) != 1) {
+                LOG_DBGF("Failed to finalise extension of shared memory map.");
                 free(dum);
                 return NULL;
         }
@@ -117,22 +103,18 @@ struct shm_du_map * shm_du_map_create()
                         0);
 
         if (shm_base == MAP_FAILED) {
-                LOG_ERR("Failed to map shared memory.");
+                LOG_DBGF("Failed to map shared memory.");
 
                 if (shm_unlink(SHM_DU_MAP_FILENAME) == -1)
-                        LOG_ERR("Failed to remove invalid shm.");
+                        LOG_DBGF("Failed to remove invalid shm.");
 
                 free(dum);
                 return NULL;
         }
-#ifdef CONFIG_OUROBOROS_DEBUG
-        memset(shm_base, 0, SHM_FILE_SIZE);
-#endif
+
         dum->shm_base = shm_base;
-        dum->ptr_du_buff = (struct shm_du_buff *)
-                ((uint8_t *) dum->shm_base + SHM_BLOCKS_SIZE);
         dum->ptr_head = (size_t *)
-                ((uint8_t *) dum->ptr_du_buff + SHM_BUFFS_SIZE);
+                ((uint8_t *) dum->shm_base + SHM_BLOCKS_SIZE);
         dum->ptr_tail = (size_t *)
                 ((uint8_t *) dum->ptr_head + sizeof(size_t));
         dum->shm_mutex = (pthread_mutex_t *)
@@ -158,7 +140,7 @@ struct shm_du_map * shm_du_map_open()
 
         shm_fd = shm_open(SHM_DU_MAP_FILENAME, O_RDWR, 0666);
         if (shm_fd == -1) {
-                LOG_ERR("Failed opening shared memory for du_buff.");
+                LOG_DBGF("Failed opening shared memory.");
                 return NULL;
         }
 
@@ -169,30 +151,32 @@ struct shm_du_map * shm_du_map_open()
                         shm_fd,
                         0);
         if (shm_base == MAP_FAILED) {
-                LOG_ERR("Failed to map shared memory.");
+                LOG_DBGF("Failed to map shared memory.");
+                if (close(shm_fd) == -1)
+                        LOG_DBGF("Failed to close invalid shm.");
 
                 if (shm_unlink(SHM_DU_MAP_FILENAME) == -1)
-                        LOG_ERR("Failed to unlink invalid shm.");
+                        LOG_DBGF("Failed to unlink invalid shm.");
 
                 return NULL;
         }
 
         dum = malloc(sizeof *dum);
         if (dum == NULL) {
-                LOG_ERR("Could not allocate struct.");
+                LOG_DBGF("Could not allocate struct.");
                 return NULL;
         }
 
         dum->shm_base = shm_base;
-        dum->ptr_du_buff = (struct shm_du_buff *)
-                ((uint8_t *) dum->shm_base + SHM_BLOCKS_SIZE);
         dum->ptr_head = (size_t *)
-                ((uint8_t *) dum->ptr_du_buff + SHM_BUFFS_SIZE);
+                ((uint8_t *) dum->shm_base + SHM_BLOCKS_SIZE);
         dum->ptr_tail = (size_t *)
                 ((uint8_t *) dum->ptr_head + sizeof(size_t));
         dum->shm_mutex = (pthread_mutex_t *)
                 ((uint8_t *) dum->ptr_tail + sizeof(size_t));
 
+        dum->fd = shm_fd;
+
         return dum;
 }
 
@@ -219,12 +203,11 @@ struct shm_du_buff * shm_create_du_buff(struct shm_du_map * dum,
                                         size_t              len)
 {
         struct shm_du_buff * sdb;
-        long                 prev_index = -1;
-        size_t               remaining = size;
-        size_t               ts = size - (headspace + len);
-        uint8_t            * read_pos = data;
-        size_t               blocks = 0;
-        int                  sz = size;
+        long                 blocks = 0;
+        int                  sz = size + sizeof *sdb;
+        int                  sz2 = headspace + len + sizeof *sdb;
+        uint8_t            * write_pos;
+        size_t               copy_len;
 
         if (dum == NULL || data == NULL) {
                 LOG_DBGF("Bogus input, bugging out.");
@@ -241,16 +224,17 @@ struct shm_du_buff * shm_create_du_buff(struct shm_du_map * dum,
                 return NULL;
         }
 
-        if (headspace > SHM_DU_BLOCK_DATA_SIZE || ts > SHM_DU_BLOCK_DATA_SIZE) {
-                LOG_ERR("Illegal du_buff: Cannot fit PCI in DU_BUFF_BLOCK.");
-                return NULL;
-        }
-
         pthread_mutex_lock(dum->shm_mutex);
 
         while (sz > 0) {
-                sz -= SHM_DU_BLOCK_DATA_SIZE;
-                blocks++;
+                sz -= SHM_DU_BUFF_BLOCK_SIZE;
+                sz2 -= SHM_DU_BUFF_BLOCK_SIZE;
+                if (sz2 < 0 && sz > 0) {
+                        pthread_mutex_unlock(dum->shm_mutex);
+                        LOG_DBG("Can't handle this packet now");
+                        return NULL;
+                }
+                ++blocks;
         }
 
         if (!shm_map_free(dum, blocks)) {
@@ -259,62 +243,23 @@ struct shm_du_buff * shm_create_du_buff(struct shm_du_map * dum,
                 return NULL;
         }
 
-        sdb = dum->ptr_du_buff + *dum->ptr_head;
+        sdb = get_head_ptr(dum);
 
         sdb->size = size;
         sdb->du_head = headspace;
         sdb->du_tail = sdb->du_head + len;
 
-        while (remaining > 0) {
-                struct shm_block * shm_buf;
-                long               bytes_to_copy = len;
-                uint8_t          * write_pos;
-
-                shm_buf = idx_to_block_ptr(dum, *(dum->ptr_head));
-
-                write_pos = (uint8_t *) shm_buf + sizeof *shm_buf;
-
-                shm_buf->size = remaining < SHM_DU_BLOCK_DATA_SIZE ?
-                        remaining : SHM_DU_BLOCK_DATA_SIZE;
-
-                bytes_to_copy = shm_buf->size;
-
-                if (remaining <= SHM_DU_BLOCK_DATA_SIZE)
-                        bytes_to_copy -= ts;
-                else if (remaining - ts <= SHM_DU_BLOCK_DATA_SIZE)
-                        shm_buf->size = remaining - ts;
-
-                remaining -= shm_buf->size;
-
-                if (prev_index == -1) {
-#ifdef CONFIG_OUROBOROS_DEBUG
-                        memset(write_pos, 0, sdb->du_head);
-#endif
-                        write_pos += sdb->du_head;
-                        bytes_to_copy -= sdb->du_head;
-                }
-
-                if (prev_index != -1)
-                        idx_to_block_ptr(dum, prev_index)->next =
-                                *(dum->ptr_head);
-
-                if (len > 0) {
-                        memcpy(write_pos, read_pos, bytes_to_copy);
-                }
-                read_pos += bytes_to_copy;
-#ifdef CONFIG_OUROBOROS_DEBUG
-                if (remaining == 0) {
-                        write_pos + = bytes_to_copy;
-                        memset(write_pos, 0, ts);
-                }
-#endif
-                shm_buf->next = -1;
-                shm_buf->prev = prev_index;
-
-                prev_index = *dum->ptr_head;
+        copy_len = MIN(len, SHM_DU_BUFF_BLOCK_SIZE - headspace - sizeof *sdb);
+        write_pos = ((uint8_t *) sdb) + sizeof *sdb + headspace;
 
+        while (blocks > 0) {
+                memcpy(write_pos, data, copy_len);
                 *(dum->ptr_head) = (*dum->ptr_head + 1)
                         & (SHM_BLOCKS_IN_MAP - 1);
+                len -= copy_len;
+                copy_len = MIN(len, SHM_DU_BUFF_BLOCK_SIZE);
+                write_pos = (uint8_t *) get_head_ptr(dum);
+                --blocks;
         }
 
         pthread_mutex_unlock(dum->shm_mutex);
@@ -324,7 +269,8 @@ struct shm_du_buff * shm_create_du_buff(struct shm_du_map * dum,
 
 int shm_release_du_buff(struct shm_du_map * dum)
 {
-        int released = 0;
+        long sz;
+        long blocks = 0;
 
         pthread_mutex_lock(dum->shm_mutex);
 
@@ -334,25 +280,22 @@ int shm_release_du_buff(struct shm_du_map * dum)
                 return -1;
         }
 
-        while (idx_to_block_ptr(dum, *dum->ptr_tail)->next != -1) {
-                *(dum->ptr_tail) = (*dum->ptr_tail + 1)
-                        & (SHM_BLOCKS_IN_MAP -1);
-                released++;
-        }
+        sz = get_tail_ptr(dum)->size;
 
-        *(dum->ptr_tail) = (*dum->ptr_tail + 1) & (SHM_BLOCKS_IN_MAP - 1);
+        while (sz + (long) sizeof (struct shm_du_buff) > 0) {
+                sz -= SHM_DU_BUFF_BLOCK_SIZE;
+                ++blocks;
+        }
 
+        *(dum->ptr_tail) = (*dum->ptr_tail + blocks) & (SHM_BLOCKS_IN_MAP - 1);
         pthread_mutex_unlock(dum->shm_mutex);
 
         return 0;
 }
 
-uint8_t * shm_du_buff_head_alloc(struct shm_du_map * dum,
-                                 struct shm_du_buff * sdb,
+uint8_t * shm_du_buff_head_alloc(struct shm_du_buff * sdb,
                                  size_t size)
 {
-        uint8_t * ret;
-
         if (sdb == NULL) {
                 LOG_DBGF("Bogus input, bugging out.");
                 return NULL;
@@ -365,17 +308,12 @@ uint8_t * shm_du_buff_head_alloc(struct shm_du_map * dum,
 
         sdb->du_head -= size;
 
-        ret = (uint8_t *) idx_to_block_ptr(dum, du_buff_ptr_to_idx(dum,sdb));
-
-        return ret + sizeof(struct shm_block) + sdb->du_head;
+        return (uint8_t *) sdb + sizeof *sdb + sdb->du_head;
 }
 
-uint8_t * shm_du_buff_tail_alloc(struct shm_du_map * dum,
-                                 struct shm_du_buff * sdb,
+uint8_t * shm_du_buff_tail_alloc(struct shm_du_buff * sdb,
                                  size_t size)
 {
-        uint8_t * ret;
-
         if (sdb == NULL) {
                 LOG_DBGF("Bogus input, bugging out.");
                 return NULL;
@@ -388,9 +326,7 @@ uint8_t * shm_du_buff_tail_alloc(struct shm_du_map * dum,
 
         sdb->du_tail += size;
 
-        ret = (uint8_t *) idx_to_block_ptr(dum, du_buff_ptr_to_idx(dum,sdb));
-
-        return ret + sizeof(struct shm_block) + sdb->du_tail;
+        return (uint8_t *) sdb + sizeof *sdb + sdb->du_tail;
 }
 
 int shm_du_buff_head_release(struct shm_du_buff * sdb,
@@ -428,5 +364,3 @@ int shm_du_buff_tail_release(struct shm_du_buff * sdb,
 
         return sdb->du_tail;
 }
-
-#endif