les: move client pool to les/vflux/server (#22495)

* les: move client pool to les/vflux/server

* les/vflux/server: un-expose NodeBalance, remove unused fn, fix bugs

* tests/fuzzers/vflux: add ClientPool fuzzer

* les/vflux/server: fixed balance tests

* les: rebase fix

* les/vflux/server: fixed more bugs

* les/vflux/server: unexported NodeStateMachine fields and flags

* les/vflux/server: unexport all internal components and functions

* les/vflux/server: fixed priorityPool test

* les/vflux/server: polish balance

* les/vflux/server: fixed mutex locking error

* les/vflux/server: priorityPool bug fixed

* common/prque: make Prque wrap-around priority handling optional

* les/vflux/server: rename funcs, small optimizations

* les/vflux/server: fixed timeUntil

* les/vflux/server: separated balance.posValue and negValue

* les/vflux/server: polish setup

* les/vflux/server: enforce capacity curve monotonicity

* les/vflux/server: simplified requestCapacity

* les/vflux/server: requestCapacity with target range, no iterations in SetCapacity

* les/vflux/server: minor changes

* les/vflux/server: moved default factors to balanceTracker

* les/vflux/server: set inactiveFlag in priorityPool

* les/vflux/server: moved related metrics to vfs package

* les/vflux/client: make priorityPool temp state logic cleaner

* les/vflux/server: changed log.Crit to log.Error

* add vflux fuzzer to oss-fuzz

Co-authored-by: rjl493456442 <garyrong0905@gmail.com>

common/prque/sstack.go

@@ -31,22 +31,24 @@ type SetIndexCallback func(data interface{}, index int)
 // the stack (heap) functionality and the Len, Less and Swap methods for the
 // sortability requirements of the heaps.
 type sstack struct {
-	setIndex SetIndexCallback
-	size     int
-	capacity int
-	offset   int
+	setIndex   SetIndexCallback
+	size       int
+	capacity   int
+	offset     int
+	wrapAround bool
 
 	blocks [][]*item
 	active []*item
 }
 
 // Creates a new, empty stack.
-func newSstack(setIndex SetIndexCallback) *sstack {
+func newSstack(setIndex SetIndexCallback, wrapAround bool) *sstack {
 	result := new(sstack)
 	result.setIndex = setIndex
 	result.active = make([]*item, blockSize)
 	result.blocks = [][]*item{result.active}
 	result.capacity = blockSize
+	result.wrapAround = wrapAround
 	return result
 }
 
@@ -94,7 +96,11 @@ func (s *sstack) Len() int {
 // Compares the priority of two elements of the stack (higher is first).
 // Required by sort.Interface.
 func (s *sstack) Less(i, j int) bool {
-	return (s.blocks[i/blockSize][i%blockSize].priority - s.blocks[j/blockSize][j%blockSize].priority) > 0
+	a, b := s.blocks[i/blockSize][i%blockSize].priority, s.blocks[j/blockSize][j%blockSize].priority
+	if s.wrapAround {
+		return a-b > 0
+	}
+	return a > b
 }
 
 // Swaps two elements in the stack. Required by sort.Interface.
@@ -110,5 +116,5 @@ func (s *sstack) Swap(i, j int) {
 
 // Resets the stack, effectively clearing its contents.
 func (s *sstack) Reset() {
-	*s = *newSstack(s.setIndex)
+	*s = *newSstack(s.setIndex, false)
 }