Deduplicate fuzz cases on the frontend before they are displayed.

fuzzer/go/deduplicator/deduplicator.go

+package deduplicator
+
+import (
+        "fmt"
+
+        "go.skia.org/infra/fuzzer/go/frontend/data"
+        "go.skia.org/infra/go/util"
+)
+
+const _MAX_STACKTRACE_LINES = 4
+
+type Deduplicator struct {
+        seen map[string]bool
+}
+
+func New() *Deduplicator {
+        return &Deduplicator{
+                seen: make(map[string]bool),
+        }
+}
+
+func (d *Deduplicator) Clear() {
+        d.seen = make(map[string]bool)
+}
+
+func (d *Deduplicator) IsUnique(report data.FuzzReport) bool {
+        // Empty stacktraces should be manually deduplicated.
+        if report.DebugStackTrace.IsEmpty() && report.ReleaseStackTrace.IsEmpty() {
+                return true
+        }
+        // Other flags should also be looked at manually.
+        if util.In("Other", report.DebugFlags) || util.In("Other", report.ReleaseFlags) {
+                return true
+        }
+        if k := key(report); d.seen[k] {
+                return false
+        } else {
+                d.seen[k] = true
+                return true
+        }
+}
+
+func key(r data.FuzzReport) string {
+        ds := trim(r.DebugStackTrace)
+        rs := trim(r.ReleaseStackTrace)
+        return fmt.Sprintf("C:%s,F:%q,F:%q,S:%s,S:%s", r.FuzzCategory, r.DebugFlags, r.ReleaseFlags, ds.String(), rs.String())
+}
+
+// trim returns a copy of the given stacktrace, with the line numbers removed and all but the
+// first _MAX_STACKTRACE_LINES stacktraces removed.
+func trim(st data.StackTrace) data.StackTrace {
+        if frames := st.Frames; len(frames) > _MAX_STACKTRACE_LINES {
+                st.Frames = st.Frames[0:_MAX_STACKTRACE_LINES]
+        }
+        // copy the frames, so we don't accidentally change the real report.
+        st.Frames = append([]data.StackTraceFrame(nil), st.Frames...)
+        // Remove line numbers from our deduping criteria.
+        for i := range st.Frames {
+                st.Frames[i].LineNumber = 0
+        }
+        return st
+}