prober: rename Probe to ProbeFunc.

Making way for a future Probe struct to encapsulate per-probe state.

Signed-off-by: David Anderson <danderson@tailscale.com>

prober/http.go

@@ -16,11 +16,11 @@ const maxHTTPBody = 4 << 20 // MiB
 
 // HTTP returns a Probe that healthchecks an HTTP URL.
 //
-// The Probe sends a GET request for url, expects an HTTP 200
+// The ProbeFunc sends a GET request for url, expects an HTTP 200
 // response, and verifies that want is present in the response
 // body. If the URL is HTTPS, the probe further checks that the TLS
 // certificate is good for at least the next 7 days.
-func HTTP(url, wantText string) Probe {
+func HTTP(url, wantText string) ProbeFunc {
 	return func(ctx context.Context) error {
 		return probeHTTP(ctx, url, []byte(wantText))
 	}

prober/prober.go

@@ -18,10 +18,10 @@ import (
 	"tailscale.com/metrics"
 )
 
-// Probe is a function that probes something and reports whether the
+// ProbeFunc is a function that probes something and reports whether the
 // probe succeeded. The provided context must be used to ensure timely
 // cancellation and timeout behavior.
-type Probe func(context.Context) error
+type ProbeFunc func(context.Context) error
 
 // a Prober manages a set of probes and keeps track of their results.
 type Prober struct {
@@ -101,7 +101,7 @@ func (p *Prober) Expvar() *metrics.Set {
 // returns.
 //
 // Registering a probe under an already-registered name panics.
-func (p *Prober) Run(name string, interval time.Duration, fun Probe) context.CancelFunc {
+func (p *Prober) Run(name string, interval time.Duration, fun ProbeFunc) context.CancelFunc {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 	ticker := p.registerLocked(name, interval)
@@ -120,7 +120,7 @@ func (p *Prober) Run(name string, interval time.Duration, fun Probe) context.Can
 
 // probeLoop invokes runProbe on fun every interval. The first probe
 // is run after interval.
-func (p *Prober) probeLoop(ctx context.Context, name string, interval time.Duration, tick ticker, fun Probe) {
+func (p *Prober) probeLoop(ctx context.Context, name string, interval time.Duration, tick ticker, fun ProbeFunc) {
 	defer func() {
 		p.unregister(name)
 		tick.Stop()
@@ -143,7 +143,7 @@ func (p *Prober) probeLoop(ctx context.Context, name string, interval time.Durat
 // fun is invoked with a timeout slightly less than interval, so that
 // the probe either succeeds or fails before the next cycle is
 // scheduled to start.
-func (p *Prober) runProbe(ctx context.Context, name string, interval time.Duration, fun Probe) {
+func (p *Prober) runProbe(ctx context.Context, name string, interval time.Duration, fun ProbeFunc) {
 	start := p.start(name)
 	defer func() {
 		// Prevent a panic within one probe function from killing the

prober/tcp.go

@@ -12,8 +12,8 @@ import (
 
 // TCP returns a Probe that healthchecks a TCP endpoint.
 //
-// The Probe reports whether it can successfully connect to addr.
-func TCP(addr string) Probe {
+// The ProbeFunc reports whether it can successfully connect to addr.
+func TCP(addr string) ProbeFunc {
 	return func(ctx context.Context) error {
 		return probeTCP(ctx, addr)
 	}

prober/tls.go

@@ -14,10 +14,10 @@ import (
 
 // TLS returns a Probe that healthchecks a TLS endpoint.
 //
-// The Probe connects to hostname, does a TLS handshake, verifies that
-// the hostname matches the presented certificate, and that the
+// The ProbeFunc connects to hostname, does a TLS handshake, verifies
+// that the hostname matches the presented certificate, and that the
 // certificate expires in more than 7 days from the probe time.
-func TLS(hostname string) Probe {
+func TLS(hostname string) ProbeFunc {
 	return func(ctx context.Context) error {
 		return probeTLS(ctx, hostname)
 	}