Add enum for duplication policy, updated readme

README.md

@@ -7,11 +7,13 @@ structure applications.
 
 ### Basics
 
-Still at the very early stages, the main concepts are
+Still at a very early stage, the main concepts are
 
+- Fixed size records, to keep things simple each record is represented by just
+  a timestamp with nanoseconds precision and a double
 - In memory segments: Data is stored in timeseries format, allowing efficient
   querying and retrieval based on timestamps, with the last slice of data in
-  memory, composed by 2 segments (currently covering 15 minutes of data each)
+  memory, composed by two segments (currently covering 15 minutes of data each)
   - The last 15 minutes of data
   - The previous 15 minutes for records out of order, totalling 30 minutes
 - Commit Log: Persistence is achieved using a commit log at the base, ensuring
@@ -22,15 +24,28 @@ Still at the very early stages, the main concepts are
 
 ### TODO
 
-- Adopt an arena for allocations
-- Text based protocol
-- TCP server
-- Memory mapped indexes
+- Duplicate points policy
+- CRC32 of records for data integrity
+- Adopt an arena for memory allocations
+- Memory mapped indexes, above a threshold enable binary search
 - Schema definitions
+- Server: Text based protocol, a simplified SQL-like would be cool
 
 ### Usage
 
-At the current stage, no server attached, just a tiny library with some crude APIs.
+At the current stage, no server attached, just a tiny library with some crude APIs;
+
+- `tsdb_init(1)` creates a new database
+- `tsdb_close(1)` closes the database
+- `ts_create(3)` creates a new timeseries in a given database
+- `ts_get(2)` retrieve an existing timeseries from a database
+- `ts_insert(3)` inserts a new point into the timeseries
+- `ts_find(3)` finds a point inside the timeseries
+- `ts_range(4)` finds a range of points in the timeseries, returning a vector
+  with the results
+- `ts_close(1)` closes a timeseries
+
+Plus a few other helpers.
 
 #### As a library
 
@@ -48,9 +63,9 @@ In the target project, a generic hello world
 
 int main(void) {
     // Example usage of timeseries library functions
-    Timeseries *ts = ts_create("example_ts");
+    Timeseries_DB *db = tsdb_init("example_ts");
     // Use timeseries functions...
-    ts_destroy(ts);
+    tsdb_close(db);
     return 0;
 }
 
@@ -74,7 +89,7 @@ int main() {
         abort();
 
     // Create a timeseries, retention is not implemented yet
-    Timeseries *ts = ts_create(db, "temperatures", 0);
+    Timeseries *ts = ts_create(db, "temperatures", 0, IGNORE);
     if (!ts)
         abort();
 

include/timeseries.h

@@ -16,6 +16,17 @@
 extern const size_t TS_FLUSH_SIZE;
 extern const size_t TS_BATCH_OFFSET;
 
+/*
+ * Enum defining the rules to apply when a duplicate point is
+ * inserted in the timeseries.
+ *
+ * It currently just support
+ * - IGNORE drops the point, returning a failure at insert attempt
+ * - INSERT just appends the point
+ * - UPDATE updates the point with the new value
+ */
+typedef enum dup_policy { IGNORE, INSERT } Duplication_Policy;
+
 /*
  * Simple record struct, wrap around a column inside the database, defined as a
  * key-val couple alike, though it's used only to describe the value of each
@@ -70,6 +81,7 @@ typedef struct timeseries {
     Timeseries_Chunk prev;
     Partition partitions[TS_MAX_PARTITIONS];
     size_t partition_nr;
+    Duplication_Policy policy;
 } Timeseries;
 
 extern int ts_init(Timeseries *ts);
@@ -93,7 +105,7 @@ extern Timeseries_DB *tsdb_init(const char *data_path);
 extern void tsdb_close(Timeseries_DB *tsdb);
 
 extern Timeseries *ts_create(const Timeseries_DB *tsdb, const char *name,
-                             int64_t retention);
+                             int64_t retention, Duplication_Policy policy);
 
 extern Timeseries *ts_get(const Timeseries_DB *tsdb, const char *name);
 

src/main.c

@@ -50,7 +50,7 @@ int main(void) {
         abort();
     }
 
-    Timeseries *ts = ts_create(db, "temperatures", 0);
+    Timeseries *ts = ts_create(db, "temperatures", 0, IGNORE);
     /* Timeseries *ts = ts_get(db, "temperatures"); */
     if (!ts) {
         log_error("Panic: mkdir");

src/timeseries.c

@@ -43,7 +43,7 @@ Timeseries_DB *tsdb_init(const char *data_path) {
 void tsdb_close(Timeseries_DB *tsdb) { free(tsdb); }
 
 Timeseries *ts_create(const Timeseries_DB *tsdb, const char *name,
-                      int64_t retention) {
+                      int64_t retention, Duplication_Policy policy) {
     if (!tsdb || !name)
         return NULL;
 
@@ -56,6 +56,7 @@ Timeseries *ts_create(const Timeseries_DB *tsdb, const char *name,
 
     ts->retention = retention;
     ts->partition_nr = 0;
+    ts->policy = policy;
     for (int i = 0; i < TS_MAX_PARTITIONS; ++i)
         memset(&ts->partitions[i], 0x00, sizeof(ts->partitions[i]));
 
@@ -96,6 +97,8 @@ Timeseries *ts_get(const Timeseries_DB *tsdb, const char *name) {
     snprintf(ts->db_data_path, DATA_PATH_SIZE, "%s", tsdb->data_path);
     snprintf(ts->name, TS_NAME_MAX_LENGTH, "%s", name);
 
+    // TODO consider adding some metadata file which saves TS info such as the
+    // duplication policy
     if (ts_init(ts) < 0) {
         ts_close(ts);
         return NULL;