new benchmark module + make the tests use it

vlib/benchmark/benchmark.v

@@ -0,0 +1,91 @@
+module benchmark
+
+import time
+
+/*
+Example usage of this module:
+```
+import benchmark
+mut bmark := benchmark.new_benchmark()
+// by default the benchmark will be verbose, i.e. it will include timing information
+// if you want it to be silent, set bmark.verbose = false 
+for { 
+   bmark.step() // call this when you want to advance the benchmark. 
+                // The timing info in bmark.step_message will be measured starting from the last call to bmark.step
+   ....
+
+   //bmark.fail() // call this if the step failed
+   //bmark.step_message(('failed')
+
+   bmark.ok() // call this when the step succeeded
+   println( bmark.step_message('ok')
+}
+bmark.stop() // call when you want to finalize the benchmark
+println( bmark.total_message('remarks about the benchmark') )
+```
+*/
+
+struct Benchmark{
+pub mut:
+	bench_start_time i64
+	bench_end_time i64
+	step_start_time i64
+	step_end_time i64
+	ntotal int
+	nok    int
+	nfail  int
+	verbose bool
+}
+
+pub fn new_benchmark() Benchmark{
+	return Benchmark{
+		bench_start_time: benchmark.now()
+		verbose: true
+	}
+}
+
+pub fn now() i64 {
+	return time.ticks()
+}
+
+pub fn (b mut Benchmark) stop() {
+	b.bench_end_time = benchmark.now()
+}
+
+pub fn (b mut Benchmark) step() {
+	b.step_start_time = benchmark.now()
+}
+
+pub fn (b mut Benchmark) fail() {
+	b.step_end_time = benchmark.now()
+	b.ntotal++
+	b.nfail++
+}
+
+pub fn (b mut Benchmark) ok() {
+	b.step_end_time = benchmark.now()
+	b.ntotal++
+	b.nok++
+}
+
+pub fn (b mut Benchmark) step_message(msg string) string {
+	return b.tdiff_in_ms(msg, b.step_start_time, b.step_end_time)
+}
+
+pub fn (b mut Benchmark) total_message(msg string) string {
+	mut tmsg := '$msg : ok, fail, total = ${b.nok:5d}, ${b.nfail:5d}, ${b.ntotal:5d}'
+	if b.verbose {
+		tmsg = '<=== total time spent $tmsg'
+	}
+	return b.tdiff_in_ms(tmsg, b.bench_start_time, b.bench_end_time)
+}
+
+////////////////////////////////////////////////////////////////////
+
+fn (b mut Benchmark) tdiff_in_ms(s string, sticks i64, eticks i64) string {
+	if b.verbose {
+		tdiff := (eticks - sticks)
+		return '${tdiff:6d} ms | $s'
+	}
+	return s
+}