.

wcfs/internal/xbtree/δbtail.go

@@ -69,7 +69,9 @@ package xbtree
 // Concurrency
 //
 // In order to allow multiple Track and queries requests to be served in
-// parallel ΔBtail employs special organization of vδT rebuild process:
+// parallel ΔBtail employs special organization of vδT rebuild process where
+// complexity of concurrency is reduced to math on merging updates to vδT and
+// trackSet, and on key range lookup:
 //
 // 1. vδT is managed under read-copy-update (RCU) discipline: before making
 //    any vδT change the mutator atomically clones whole vδT and applies its
@@ -117,13 +119,21 @@ package xbtree
 //
 //	vδT/(T₁∪T₂) = vδT/T₁ | vδT/T₂
 //
-//    i.e. vδT computed for tracked set being union of T₁ and T₂ is the same
-//    as merge of vδT computed for tracked set T₁ and vδT computed for tracked
-//    set T₂.
+//      ( i.e. vδT computed for tracked set being union of T₁ and T₂ is the
+//        same as merge of vδT computed for tracked set T₁ and vδT computed
+//	  for tracked set T₂ )
 //
-//    this merge property allows to run computation for δ(vδT) independently
-//    and with ΔBtail unlocked, which in turn enables running several
-//    Track/queries in parallel.
+//    and that
+//
+//	trackSet | (δPP₁|δPP₂) = (trackSet|δPP₁) | (trackSet|δPP₂)
+//
+//	( i.e. tracking set updated for union of δPP₁ and δPP₂ is the same
+//	  as union of tracking set updated with δPP₁ and tracking set updated
+//	  with δPP₂ )
+//
+//    these merge properties allow to run computation for δ(vδT) and δ(trackSet)
+//    independently and with ΔBtail unlocked, which in turn enables running
+//    several Track/queries in parallel.
 //
 // 4. while vδT rebuild is being run, krebuildJobs keeps corresponding keycov
 //    entry to indicate in-progress rebuild. Should a query need vδT for keys