Refactor exvar to use interface types, and add mapVar.
R=r
APPROVED=r
DELTA=170 (136 added, 6 deleted, 28 changed)
OCL=27628
CL=27652
diff --git a/src/lib/exvar.go b/src/lib/exvar.go
index 319a097..88f36b7 100644
--- a/src/lib/exvar.go
+++ b/src/lib/exvar.go
@@ -11,44 +11,141 @@
"sync";
)
+// If mismatched names are used (e.g. calling IncrementInt on a mapVar), the
+// var name is silently mapped to these. We will consider variables starting
+// with reservedPrefix to be reserved by this package, and so we avoid the
+// possibility of a user doing IncrementInt("x-mismatched-map", 1).
+// TODO(dsymonds): Enforce this.
+const (
+ reservedPrefix = "x-";
+ mismatchedInt = reservedPrefix + "mismatched-int";
+ mismatchedMap = reservedPrefix + "mismatched-map";
+)
+
+// exVar is an abstract type for all exported variables.
+type exVar interface {
+ String() string;
+}
+
+// intVar is an integer variable, and satisfies the exVar interface.
+type intVar int;
+
+func (i intVar) String() string {
+ return fmt.Sprint(int(i))
+}
+
+// mapVar is a map variable, and satisfies the exVar interface.
+type mapVar map[string] int;
+
+func (m mapVar) String() string {
+ s := "map:x"; // TODO(dsymonds): the 'x' should be user-specified!
+ for k, v := range m {
+ s += fmt.Sprintf(" %s:%v", k, v)
+ }
+ return s
+}
+
+// TODO(dsymonds):
+// - string-valued vars
+// - dynamic lookup vars (via chan?)
+
// Global state.
var (
mutex sync.Mutex;
- intVars = make(map[string] int);
- mapVars = make(map[string] map[string] int);
- // TODO(dsymonds):
- // - string-valued vars
- // - docstrings
- // - dynamic lookup vars (via chan)
+ vars = make(map[string] exVar);
+ // TODO(dsymonds): docstrings
)
-// Increment adds inc to the var called name.
-func Increment(name string, inc int) {
+// getOrInitIntVar either gets or initializes an intVar called name.
+// Callers should already be holding the mutex.
+func getOrInitIntVar(name string) *intVar {
+ if v, ok := vars[name]; ok {
+ // Existing var
+ if iv, ok := v.(*intVar); ok {
+ return iv
+ }
+ // Type mismatch.
+ return getOrInitIntVar(mismatchedInt)
+ }
+ // New var
+ iv := new(intVar);
+ vars[name] = iv;
+ return iv
+}
+
+// getOrInitMapVar either gets or initializes a mapVar called name.
+// Callers should already be holding the mutex.
+func getOrInitMapVar(name string) *mapVar {
+ if v, ok := vars[name]; ok {
+ // Existing var
+ if mv, ok := v.(*mapVar); ok {
+ return mv
+ }
+ // Type mismatch.
+ return getOrInitMapVar(mismatchedMap)
+ }
+ // New var
+ var m mapVar = make(map[string] int);
+ vars[name] = &m;
+ return &m
+}
+
+// IncrementInt adds inc to the integer-valued var called name.
+func IncrementInt(name string, inc int) {
mutex.Lock();
defer mutex.Unlock();
- if x, ok := intVars[name]; ok {
- intVars[name] += inc
+ *getOrInitIntVar(name) += inc
+}
+
+// IncrementMap adds inc to the keyed value in the map-valued var called name.
+func IncrementMap(name string, key string, inc int) {
+ mutex.Lock();
+ defer mutex.Unlock();
+
+ mv := getOrInitMapVar(name);
+ // TODO(dsymonds): Change this to just mv[key] when bug143 is fixed.
+ if v, ok := (*mv)[key]; ok {
+ mv[key] += inc
} else {
- intVars[name] = inc
+ mv[key] = inc
}
}
-// Set sets the var called name to value.
-func Set(name string, value int) {
+// SetInt sets the integer-valued var called name to value.
+func SetInt(name string, value int) {
mutex.Lock();
defer mutex.Unlock();
- intVars[name] = value
+ *getOrInitIntVar(name) = value
}
-// Get retrieves an integer-valued var called name.
-func Get(name string) (x int, ok bool) {
- x, ok = intVars[name];
- return
+// SetMap sets the keyed value in the map-valued var called name.
+func SetMap(name string, key string, value int) {
+ mutex.Lock();
+ defer mutex.Unlock();
+
+ getOrInitMapVar(name)[key] = value
}
-// TODO(dsymonds): Functions for map-valued vars.
+// GetInt retrieves an integer-valued var called name.
+func GetInt(name string) int {
+ mutex.Lock();
+ defer mutex.Unlock();
+
+ return *getOrInitIntVar(name)
+}
+
+// GetMap retrieves the keyed value for a map-valued var called name.
+func GetMap(name string, key string) int {
+ mutex.Lock();
+ defer mutex.Unlock();
+
+ // TODO(dsymonds): Change this to just getOrInitMapVar(name)[key] when
+ // bug143 is fixed.
+ x, ok := (*getOrInitMapVar(name))[key];
+ return x
+}
// String produces a string of all the vars in textual format.
func String() string {
@@ -56,7 +153,7 @@
defer mutex.Unlock();
s := "";
- for name, value := range intVars {
+ for name, value := range vars {
s += fmt.Sprintln(name, value)
}
return s
diff --git a/src/lib/exvar_test.go b/src/lib/exvar_test.go
index 2948fc6..6b309f3 100644
--- a/src/lib/exvar_test.go
+++ b/src/lib/exvar_test.go
@@ -11,19 +11,17 @@
)
func TestSimpleCounter(t *testing.T) {
- // Unknown exvar should be zero, and return !ok.
- x, ok := Get("requests");
- if x != 0 || ok {
- t.Errorf("Get(nonexistent) = (%v, %v), want (%v, %v)",
- x, ok, 0, false)
+ // Unknown exvar should be zero.
+ x := GetInt("requests");
+ if x != 0 {
+ t.Errorf("Get(nonexistent) = %v, want 0", x)
}
- Increment("requests", 1);
- Increment("requests", 3);
- x, ok = Get("requests");
- if x != 4 || !ok {
- t.Errorf("Get('requests') = (%v, %v), want (%v, %v)",
- x, ok, 4, true)
+ IncrementInt("requests", 1);
+ IncrementInt("requests", 3);
+ x = GetInt("requests");
+ if x != 4 {
+ t.Errorf("Get('requests') = %v, want 4", x)
}
out := String();
@@ -33,22 +31,57 @@
}
}
+func TestMismatchedCounters(t *testing.T) {
+ // Make sure some vars exist.
+ GetInt("requests");
+ GetMap("colours", "red");
+
+ IncrementInt("colours", 1);
+ if x := GetInt("x-mismatched-int"); x != 1 {
+ t.Errorf("GetInt('x-mismatched-int') = %v, want 1", x)
+ }
+
+ IncrementMap("requests", "orange", 1);
+ if x := GetMap("x-mismatched-map", "orange"); x != 1 {
+ t.Errorf("GetMap('x-mismatched-int', 'orange') = %v, want 1", x)
+ }
+}
+
+func TestMapCounter(t *testing.T) {
+ // Unknown exvar should be zero.
+ if x := GetMap("colours", "red"); x != 0 {
+ t.Errorf("GetMap(non, existent) = %v, want 0", x)
+ }
+
+ IncrementMap("colours", "red", 1);
+ IncrementMap("colours", "red", 2);
+ IncrementMap("colours", "blue", 4);
+ if x := GetMap("colours", "red"); x != 3 {
+ t.Errorf("GetMap('colours', 'red') = %v, want 3", x)
+ }
+ if x := GetMap("colours", "blue"); x != 4 {
+ t.Errorf("GetMap('colours', 'blue') = %v, want 4", x)
+ }
+
+ // TODO(dsymonds): Test String()
+}
+
func hammer(name string, total int, done chan <- int) {
for i := 0; i < total; i++ {
- Increment(name, 1)
+ IncrementInt(name, 1)
}
done <- 1
}
func TestHammer(t *testing.T) {
- Set("hammer-times", 0);
+ SetInt("hammer-times", 0);
sync := make(chan int);
hammer_times := int(1e5);
go hammer("hammer-times", hammer_times, sync);
go hammer("hammer-times", hammer_times, sync);
<-sync;
<-sync;
- if final, ok := Get("hammer-times"); final != 2 * hammer_times {
+ if final := GetInt("hammer-times"); final != 2 * hammer_times {
t.Errorf("hammer-times = %v, want %v", final, 2 * hammer_times)
}
}
