Document concurrency issues. Fixes #5.

Makefile

-# Copyright 2014 The b Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style
-# license that can be found in the LICENSE file.
+.PHONY:	all clean cover cpu editor internalError later mem nuke todo edit
 
-.PHONY: all todo clean cover generic mem nuke cpu
-
-testbin=b.test
+grep=--include=*.go --include=*.l --include=*.y --include=*.yy
+ngrep='TODOOK\|parser\.go\|scanner\.go\|.*_string\.go'
 
 all: editor
-	go build
-	go vet
-	golint .
-	go install
+	go vet 2>&1 | grep -v $(ngrep) || true
+	golint 2>&1 | grep -v $(ngrep) || true
 	make todo
-
-editor:
-	gofmt -l -s -w .
-	go test -i
-	go test
+	-unused .
+	-misspell *.go
+	-gosimple
 
 clean:
-	@go clean
-	rm -f *~ *.out $(testbin)
+	go clean
+	rm -f *~ *.test *.out
 
 cover:
 	t=$(shell tempfile) ; go test -coverprofile $$t && go tool cover -html $$t && unlink $$t
 
-cpu:
-	go test -c
-	./$(testbin) -test.cpuprofile cpu.out
-	go tool pprof --lines $(testbin) cpu.out
+cpu: clean
+	go test -run @ -bench . -cpuprofile cpu.out
+	go tool pprof -lines *.test cpu.out
+
+edit:
+	@ 1>/dev/null 2>/dev/null gvim -p Makefile *.go
+
+editor:
+	gofmt -l -s -w *.go
+	go test
+	go build
 
 generic:
 	@# writes to stdout a version where the type of key is KEY and the type
@@ -38,16 +38,22 @@ generic:
 	@# the output with your desired types.
 	@sed -e 's|interface{}[^{]*/\*K\*/|KEY|g' -e 's|interface{}[^{]*/\*V\*/|VALUE|g' btree.go
 
-mem:
-	go test -c
-	./$(testbin) -test.bench . -test.memprofile mem.out -test.memprofilerate 1
-	go tool pprof --lines --web --alloc_space $(testbin) mem.out
+internalError:
+	egrep -ho '"internal error.*"' *.go | sort | cat -n
+
+later:
+	grep -n $(grep) LATER * || true
+	grep -n $(grep) MAYBE * || true
+
+mem: clean
+	go test -run @ -bench . -memprofile mem.out -memprofilerate 1 -timeout 24h
+	go tool pprof -lines -web -alloc_space *.test mem.out
 
 nuke: clean
-	rm -f *.test *.out
+	go clean -i
 
 todo:
-	@grep -n ^[[:space:]]*_[[:space:]]*=[[:space:]][[:alpha:]][[:alnum:]]* *.go || true
-	@grep -n TODO *.go || true
-	@grep -n BUG *.go || true
-	@grep -n println *.go || true
+	grep -nr $(grep) ^[[:space:]]*_[[:space:]]*=[[:space:]][[:alpha:]][[:alnum:]]* * | grep -v $(ngrep) || true
+	grep -nr $(grep) TODO * | grep -v $(ngrep) || true
+	grep -nr $(grep) BUG * | grep -v $(ngrep) || true
+	grep -nr $(grep) [^[:alpha:]]println * | grep -v $(ngrep) || true

all_test.go

@@ -36,13 +36,17 @@ func dbg(s string, va ...interface{}) {
 	fmt.Println()
 }
 
-func TODO(...interface{}) string {
+func TODO(...interface{}) string { //TODOOK
 	_, fn, fl, _ := runtime.Caller(1)
-	return fmt.Sprintf("TODO: %s:%d:\n", path.Base(fn), fl)
+	return fmt.Sprintf("TODO: %s:%d:\n", path.Base(fn), fl) //TODOOK
 }
 
 func use(...interface{}) {}
 
+func init() {
+	use(caller, dbg, TODO, isNil, (*Tree).dump) //TODOOK
+}
+
 // ============================================================================
 
 func isNil(p interface{}) bool {

doc.go

@@ -6,10 +6,30 @@
 //
 // Changelog
 //
+// 2016-07-16: Update becnhmark results to newer Go version. Add a note on
+// concurrency.
+//
 // 2014-06-26: Lower GC presure by recycling things.
 //
 // 2014-04-18: Added new method Put.
 //
+// Concurrency considerations
+//
+// Tree.{Clear,Delete,Put,Set} mutate the tree. One can use eg. a
+// sync.Mutex.Lock/Unlock (or sync.RWMutex.Lock/Unlock) to wrap those calls if
+// they are to be invoked concurrently.
+//
+// Tree.{First,Get,Last,Len,Seek,SeekFirst,SekLast} read but do not mutate the
+// tree.  One can use eg. a sync.RWMutex.RLock/RUnlock to wrap those calls if
+// they are to be invoked concurrently with any of the tree mutating methods.
+//
+// Enumerator.{Next,Prev} mutate the enumerator and read but not mutate the
+// tree.  One can use eg. a sync.RWMutex.RLock/RUnlock to wrap those calls if
+// they are to be invoked concurrently with any of the tree mutating methods. A
+// separate mutex for the enumerator, or the whole tree in a simplified
+// variant, is necessary if the enumerator's Next/Prev methods per se are to
+// be invoked concurrently.
+//
 // Generic types
 //
 // Keys and their associated values are interface{} typed, similar to all of
@@ -34,20 +54,20 @@
 // No other changes to int.go are necessary, it compiles just fine.
 //
 // Running the benchmarks for 1000 keys on a machine with Intel i5-4670 CPU @
-// 3.4GHz, Go release 1.4.2.
+// 3.4GHz, Go 1.7rc1.
 //
 //	$ go test -bench 1e3 example/all_test.go example/int.go
+//	BenchmarkSetSeq1e3-4    	   20000	     78265 ns/op
+//	BenchmarkGetSeq1e3-4    	   20000	     67980 ns/op
+//	BenchmarkSetRnd1e3-4    	   10000	    172720 ns/op
+//	BenchmarkGetRnd1e3-4    	   20000	     89539 ns/op
+//	BenchmarkDelSeq1e3-4    	   20000	     87863 ns/op
+//	BenchmarkDelRnd1e3-4    	   10000	    130891 ns/op
+//	BenchmarkSeekSeq1e3-4   	   10000	    100118 ns/op
+//	BenchmarkSeekRnd1e3-4   	   10000	    121684 ns/op
+//	BenchmarkNext1e3-4      	  200000	      6330 ns/op
+//	BenchmarkPrev1e3-4      	  200000	      9066 ns/op
 //	PASS
-//	BenchmarkSetSeq1e3	   10000	    151620 ns/op
-//	BenchmarkGetSeq1e3	   10000	    115354 ns/op
-//	BenchmarkSetRnd1e3	    5000	    255865 ns/op
-//	BenchmarkGetRnd1e3	   10000	    140466 ns/op
-//	BenchmarkDelSeq1e3	   10000	    143860 ns/op
-//	BenchmarkDelRnd1e3	   10000	    188228 ns/op
-//	BenchmarkSeekSeq1e3	   10000	    156448 ns/op
-//	BenchmarkSeekRnd1e3	   10000	    190587 ns/op
-//	BenchmarkNext1e3	  200000	      9407 ns/op
-//	BenchmarkPrev1e3	  200000	      9306 ns/op
-//	ok  	command-line-arguments	26.369s
+//	ok  	command-line-arguments	42.531s
 //	$
 package b