[alerts-dispatcher] update to build again :) also fixes a concurrent map access

go/src/infra/monitoring/analyzer/gatekeeper.go

Index: go/src/infra/monitoring/analyzer/gatekeeper.go
diff --git a/go/src/infra/monitoring/analyzer/gatekeeper.go b/go/src/infra/monitoring/analyzer/gatekeeper.go
new file mode 100644
index 0000000000000000000000000000000000000000..f295f9158359c911da02cb67e08ea47cbe9c42c8
--- /dev/null
+++ b/go/src/infra/monitoring/analyzer/gatekeeper.go
@@ -0,0 +1,105 @@
+package analyzer
+
+import (
+	"strings"
+
+	"infra/monitoring/messages"
+)
+
+// GatekeeperRules implements the rule checks that gatekeeper performs
+// on failures to determine if the failure should close the tree.
+type GatekeeperRules struct {
+	cfg messages.GatekeeperConfig
+}
+
+// NewGatekeeperRules returns a new instance of GatekeeperRules initialized
+// with cfg.
+func NewGatekeeperRules(cfg messages.GatekeeperConfig) *GatekeeperRules {
+	ret := &GatekeeperRules{cfg}
+	for masterURL, masterCfgs := range cfg.Masters {
+		if len(masterCfgs) != 1 {
+			log.Errorf("Multiple configs for master: %s", masterURL)
+		}
+		parts := strings.Split(masterURL, "/")
+		masterName := parts[len(parts)-1]
+		ret.cfg.Masters[masterName] = masterCfgs
+	}
+	return ret
+}
+
+// WouldCloseTree returns true if a step failure on given builder/master would
+// cause it to close the tree.
+func (r *GatekeeperRules) WouldCloseTree(master, builder, step string) bool {
+	mcs, ok := r.cfg.Masters[master]
+	if !ok {
+		log.Errorf("Missing master cfg: %s", master)
+		return false
+	}
+	mc := mcs[0]
+	bc, ok := mc.Builders[builder]
+	if !ok {
+		bc, ok = mc.Builders["*"]
+		if !ok {
+			return false
+		}
+	}
+
+	// TODO: Check for cfg.Categories
+	for _, xstep := range bc.ExcludedSteps {
+		if xstep == step {
+			return false
+		}
+	}
+
+	csteps := []string{}
+	csteps = append(csteps, bc.ClosingSteps...)
+	csteps = append(csteps, bc.ClosingOptional...)
+
+	for _, cs := range csteps {
+		if cs == "*" || cs == step {
+			return true
+		}
+	}
+
+	return false
+}
+
+// ExcludeFailure returns true if a step failure whould be ignored.
+func (r *GatekeeperRules) ExcludeFailure(master, builder, step string) bool {
+	mcs, ok := r.cfg.Masters[master]
+	if !ok {
+		log.Errorf("Can't filter unknown master %s", master)
+		return false
+	}
+	mc := mcs[0]
+
+	for _, ebName := range mc.ExcludedBuilders {
+		if ebName == "*" || ebName == builder {
+			return true
+		}
+	}
+
+	// Not clear that builder_alerts even looks at the rest of these conditions
+	// even though they're specified in gatekeeper.json
+	for _, s := range mc.ExcludedSteps {
+		if step == s {
+			return true
+		}
+	}
+
+	bc, ok := mc.Builders[builder]
+	if !ok {
+		if bc, ok = mc.Builders["*"]; !ok {
+			log.Warningf("Unknown %s builder %s", master, builder)
+			return true
+		}
+	}
+
+	for _, esName := range bc.ExcludedSteps {
+		if esName == step || esName == "*" {
+			return true
+		}
+	}
+
+	return false
+}