API: valueAvailable() - the number of (value) bytes available for reading, recordsNumber() - total number of records in CDB

Author: JulStrat

README.md

@@ -19,6 +19,10 @@ int readValue();
 
 int readValue(void *buff, unsigned int byteNum);
 
+unsigned long recordsNumber();
+
+unsigned long valueAvailable();
+
 cdbResult close();
 ```    
 

examples/airports/airports.ino

@@ -69,7 +69,7 @@ void query(const void *key, unsigned long keyLen) {
 
 void setup() {
   const char fileName[] = "airports.cdb";
-  const char *air[] = {"SBGL", "00AR", "PG-TFI", "US-0480"};
+  const char *air[] = {"SBGL", "00AR", "PG-TFI", "US-0480", "ZYGH"};
 
   Serial.begin(9600);
   while (!Serial) {
@@ -79,6 +79,8 @@ void setup() {
   SD.begin(10);
 
   if (ucdb.open(fileName) == CDB_OK) {
+    Serial.print("Total records number: ");
+    Serial.println(ucdb.recordsNumber());
     // Find some existing codes.
     for (unsigned int i = 0; i < sizeof (air) / sizeof (const char *); i++) {
       query(air[i], strlen(air[i]));

examples/airports/airports.png

@@ -48,6 +48,9 @@ void loop() {
     return;
   }
 
+  Serial.print("Total records number: ");
+  Serial.println(ucdb.recordsNumber());
+
   Serial.println("Querying 1000 random keys from interval [0, 5000000)...");
   startMillis = millis();
   for (int i = 0; i < 1000; ++i) {
@@ -144,6 +147,8 @@ void loop() {
     rt = ucdb.findKey(str, strlen(str));
 
     if (rt == KEY_FOUND) {
+      Serial.print("Value length in bytes: ");
+      Serial.println(ucdb.valueAvailable());
       br = ucdb.readValue(str, 15);
       if (br >= 0) {
         str[br] = '\0';

examples/benchmark/benchmark.ino

@@ -1,5 +1,5 @@
 name=uCDB
-version=0.4.2
+version=0.4.3
 author=Ioulianos Kakoulidis
 maintainer=Ioulianos Kakoulidis <ioulianos.kakoulidis@hotmail.com>
 sentence=API for querying Constant DataBase file store.

examples/benchmark/benchmark.png

@@ -23,6 +23,10 @@ uCDB::uCDB() {
 cdbResult uCDB::open(const char *fileName, unsigned long (*userHashFunc)(const void *key, unsigned long keyLen)) {
   unsigned long htPos;
   unsigned long htSlotsNum;
+
+  unsigned long dend;
+  unsigned long snum;
+  
   byte buff[CDB_DESCRIPTOR_SIZE];
 
   zero();
@@ -43,8 +47,8 @@ cdbResult uCDB::open(const char *fileName, unsigned long (*userHashFunc)(const v
     return (state = CDB_ERROR);
   }
 
-  dataEndPos = cdb.size();
-  slotsNum = 0;
+  dend = cdb.size();
+  snum = 0;
 
   for (unsigned long pos = 0; pos < CDB_HEADER_SIZE; pos += CDB_DESCRIPTOR_SIZE) {
     if (!readDescriptor(buff, pos)) {
@@ -65,20 +69,22 @@ cdbResult uCDB::open(const char *fileName, unsigned long (*userHashFunc)(const v
     }
 
     // Adjust data end position and total slots number
-    if (htPos < dataEndPos) {
-      dataEndPos = htPos;
+    if (htPos < dend) {
+      dend = htPos;
     }
-    slotsNum += htSlotsNum;
+    snum += htSlotsNum;
 
-    if (((cdb.size() - dataEndPos) >> 3) < slotsNum) {
+    if (((cdb.size() - dend) >> 3) < snum) {
       return (state = CDB_ERROR); // Critical CDB format or data integrity error          
     }
   }
   // Check total
-  if ((cdb.size() - dataEndPos) != 8 * slotsNum){
+  if ((cdb.size() - dend) != 8 * snum){
     return (state = CDB_ERROR); // Critical CDB format or data integrity error           
   }
 
+  dataEndPos = dend;
+  slotsNum = snum;
   hashFunc = userHashFunc;
   return (state = CDB_OK);
 }
@@ -219,6 +225,14 @@ int uCDB::readValue(void *buff, unsigned int byteNum) {
   return -1;
 }
 
+unsigned long uCDB::recordsNumber() {
+  return (slotsNum >> 1);  
+}
+
+unsigned long uCDB::valueAvailable() {
+  return ((state == KEY_FOUND) ? valueBytesAvail : 0);
+}
+
 cdbResult uCDB::close() {
   zero();  
   cdb.close();
@@ -267,6 +281,9 @@ bool uCDB::readDescriptor(byte *buff, unsigned long pos) {
 }
 
 void uCDB::zero() {
+  dataEndPos = 0;
+  slotsNum = 0;
+    
   slotsToScan = 0;
   nextSlotPos = 0;
 }

library.properties

@@ -59,6 +59,16 @@ class uCDB
         after successful finKey() or findNextValue() call
     */
     int readValue(void *buff, unsigned int byteNum);
+    
+    /**
+        Total records number in CDB
+    */
+    unsigned long recordsNumber();
+
+    /**
+        The number of `value' bytes available for reading
+    */
+    unsigned long valueAvailable();
 
     /**
         Close CDB
@@ -73,8 +83,8 @@ class uCDB
     unsigned long keyLen_;
     unsigned long keyHash;
 
-    unsigned long dataEndPos;
-    unsigned long slotsNum;
+    unsigned long dataEndPos; ///< Data end position
+    unsigned long slotsNum;   ///< Total slots number in CDB.
 
     /// @name Hash table descriptor (HEADER section)
     /// @{