Merge pull request #101 from bonitoo-io/fix/memory_alloc

fix(memory): better string concatenation

Author: vlastahajek

CHANGELOG.md

@@ -13,10 +13,11 @@
 
 ### Documentation
  - [#87](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/87) - Fixed include file name in the Readme
- - [#99](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/99) - Changed default InfluxDB 2 port from 9999 to 8086 (default since rc0)
+ - [#99](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/99) - Changed default InfluxDB 2 port from 9999 to 8086 (default since InfluxDB 2 RC0)
 
 ### Fixes
  - [#90](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/90) - Fixed boolean type recognition of InfluxDB Flux
+ - [#101](https://github.com/tobiasschuerg/InfluxDB-Client-for-Arduino/pull/101) - Better memory efficient point line composition
 
 ## Version 3.3.0 (2020-07-07)
  - [NEW] Added possibility skip server certification validation (`setInsecure()` method)

src/Point.cpp

@@ -61,14 +61,18 @@ void Point::putField(String name, String value) {
 
 String Point::toLineProtocol() const {
     String line =  _measurement;
+    line.reserve(1 + _tags.length() + 1 + _fields.length() + 1 + _timestamp.length());
     if(hasTags()) {
-        line += "," + _tags;
+        line += ",";
+        line += _tags;
     }
     if(hasFields()) {
-        line += " " + _fields;
+        line += " ";
+        line += _fields;
     }
     if(hasTime()) {
-        line += " " + _timestamp;
+        line += " ";
+        line += _timestamp;
     }
     return line;
 }
@@ -105,10 +109,10 @@ void  Point::setTime(String timestamp) {
 }
 
 void  Point::clearFields() {
-    _fields = "";
-    _timestamp = "";
+    _fields = (char *)nullptr;
+    _timestamp = (char *)nullptr;
 }
 
 void Point:: clearTags() {
-    _tags = "";
+    _tags = (char *)nullptr;
 }