Improved readString() for File

[apicquot]

readString() method for the class File is inherited from the class Stream that requires a timeout of 1 second at the end of the file, hence a very poor performance. Stream implementation also uses multiple memory resizing that could be anticipated based on the size of the file.

The proposed implementation solves these two issues.

[devyte]

After discussion with @earlephilhower , this implementation is also suboptimal. Implementation should be in terms of the File implementation read(buf, size) method. To avoid large mem use, it should be chunked, e.g.: 128 or 256 bytes at a time, along the lines of how this write method is implemented:

Arduino/libraries/ESP8266WiFi/src/WiFiClientSecureBearSSL.cpp

Line 310 in a9fb6db

do {

[apicquot]

may want to use a define rather than sizeof for the size of the block to read ?

[devyte]

The function sizeof is compile-time code, so it gets optimized to a single value. Your use of sizeof is correct. The number 256 should be in a macro, though.

[devyte]

ping!

[apicquot]

I don't understand, the code works for me for files<256 or files>= 256: I read and push blocks while countRead>0.

The test countRead<sizeof(temp) is just to place a string terminator for the last block.

[devyte]

Apologies, my previous review comment was messed up. It's corrected now.

[apicquot]

You are absolutely right @devyte : String::concat(char*) needs a string terminator to work. I fixed it.

string::concat(char*, int length) may have been more elegant but it is a protected method