Various improvements.

* Expand README.md, provide benchmark results.
* Add docs, benchmarks for binheap and circ packages.
* Add methods Len() and Capacity().
* Change *sync.Cond to sync.Cond.
* TryRecv() and TrySend() distinguish empty and closed errors.
* Improve test coverage.
* Add basic Makefile.
* Fix documentation mistakes.

circ/lib.go

@@ -9,12 +9,22 @@ type B[T any] struct {
 	tail int
 }
 
-// Make creates a new circular buffer.
+// Make creates a new buffer.
 func Make[T any](cap int) B[T] {
 	buf := make([]T, cap)
 	return B[T]{buf: buf}
 }
 
+// Capacity returns the total capacity of the buffer.
+func (b *B[T]) Capacity() int {
+	return cap(b.buf)
+}
+
+// Len returns the number of items in the buffer.
+func (b *B[T]) Len() int {
+	return b.len
+}
+
 // CanPush returns true if the buffer has space for new items.
 func (b *B[T]) CanPush() bool {
 	return cap(b.buf)-b.len != 0
@@ -32,9 +42,9 @@ func (b *B[T]) PopFront() T {
 	if !b.CanPop() {
 		panic("cannot pop from empty buffer")
 	}
-	var empty T
 	item := b.buf[b.head]
-	// clear buffer slot so that we don't hold on to garbage
+	// clear buffer slot so as not to hold on to garbage
+	var empty T
 	b.buf[b.head] = empty
 	b.len--
 	b.head++

circ/lib_test.go

@@ -1,6 +1,7 @@
 package circ_test
 
 import (
+	"math/rand"
 	"testing"
 
 	"gogs.humancabbage.net/sam/priorityq/circ"
@@ -9,11 +10,17 @@ import (
 func TestRepeatPushPop(t *testing.T) {
 	t.Parallel()
 	cb := circ.Make[int](4)
+	if cb.Capacity() != 4 {
+		t.Errorf("wrong capacity")
+	}
 	for i := 0; i < 50; i++ {
 		cb.PushBack(1)
 		cb.PushBack(2)
 		cb.PushBack(3)
 		cb.PushBack(4)
+		if cb.Len() != 4 {
+			t.Errorf("wrong length")
+		}
 		checkPop := func(n int) {
 			if v := cb.PopFront(); v != n {
 				t.Errorf("popped %d, expected %d", v, n)
@@ -65,3 +72,30 @@ func TestFullPushPanic(t *testing.T) {
 	cb.PushBack(1)
 	cb.PushBack(2)
 }
+
+func BenchmarkPush(b *testing.B) {
+	cb := circ.Make[int](b.N)
+	rs := rand.NewSource(0)
+	r := rand.New(rs)
+	items := make([]int, b.N)
+	for i := 0; i < b.N; i++ {
+		items[i] = r.Int()
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		cb.PushBack(items[i])
+	}
+}
+
+func BenchmarkPop(b *testing.B) {
+	cb := circ.Make[int](b.N)
+	rs := rand.NewSource(0)
+	r := rand.New(rs)
+	for i := 0; i < b.N; i++ {
+		cb.PushBack(r.Int())
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		cb.PopFront()
+	}
+}