#include "common.h"
#include "txn.h"
#include "mem.h"
+#include "skiplist.h"
#define UNDETERMINED_VERSION 0
#define INITIAL_WRITES_SIZE 4
uint32_t writes_size;
uint32_t writes_count;
uint32_t writes_scan;
- txn_access_e access;
- txn_isolation_e isolation;
+ txn_type_e type;
txn_state_e state;
};
+static uint64_t version_ = 1;
+
static txn_state_e txn_validate (txn_t *txn);
-static uint64_t version_ = 1;
+static map_t *active_ = NULL;
+
+void txn_init (void) {
+ active_ = map_alloc(MAP_TYPE_SKIPLIST, NULL);
+}
// Validate the updates for <key>. Validation fails for a key we have written to if there is a
// write committed newer than our read version.
return u;
}
-txn_t *txn_begin (txn_access_e access, txn_isolation_e isolation, map_t *map) {
+txn_t *txn_begin (txn_type_e type, map_t *map) {
txn_t *txn = (txn_t *)nbd_malloc(sizeof(txn_t));
memset(txn, 0, sizeof(txn_t));
- txn->access = access;
- txn->isolation = isolation;
- txn->rv = version_;
+ txn->type = type;
txn->wv = UNDETERMINED_VERSION;
txn->state = TXN_RUNNING;
txn->map = map;
- if (isolation != TXN_READ_ONLY) {
+ if (type != TXN_READ_ONLY) {
txn->writes = nbd_malloc(sizeof(*txn->writes) * INITIAL_WRITES_SIZE);
txn->writes_size = INITIAL_WRITES_SIZE;
}
+
+ // aquire the read version for txn.
+ do {
+ txn->rv = version_;
+
+ uint64_t old_count;
+ uint64_t temp = 0;
+ do {
+ old_count = temp;
+ temp = (uint64_t)map_cas(active_, (void *)txn->rv, old_count, old_count + 1);
+ } while (temp != old_count);
+
+ if (txn->rv == version_)
+ break;
+
+ temp = 1;
+ do {
+ old_count = temp;
+ temp = map_cas(active_, (void *)txn->rv, old_count, old_count - 1);
+ } while (temp != old_count);
+ } while (1);
+
return txn;
}