rework indexing strategy to use an enum (#694)

codex/erasure/erasure.nim

@@ -130,10 +130,10 @@ proc prepareEncodingData(
   ##
 
   let
-    strategy = SteppedIndexingStrategy.new(
+    strategy = SteppedStrategy.init(
       firstIndex = 0,
       lastIndex = params.rounded - 1,
-      numberOfIterations = params.steps
+      iterations = params.steps
     )
     indicies = toSeq(strategy.getIndicies(step))
     pendingBlocksIter = self.getPendingBlocks(manifest, indicies.filterIt(it < manifest.blocksCount))
@@ -179,10 +179,10 @@ proc prepareDecodingData(
   ##
 
   let
-    strategy = SteppedIndexingStrategy.new(
+    strategy = SteppedStrategy.init(
       firstIndex = 0,
       lastIndex = encoded.blocksCount - 1,
-      numberOfIterations = encoded.steps
+      iterations = encoded.steps
     )
     indicies = toSeq(strategy.getIndicies(step))
     pendingBlocksIter = self.getPendingBlocks(encoded, indicies)

codex/indexingstrategy.nim

@@ -1,12 +1,23 @@
-import std/sequtils
-
 import ./errors
 import ./utils
 import ./utils/asynciter
 
 {.push raises: [].}
 
 type
+  StrategyType* = enum
+    # Simplest approach:
+    # 0 => 0, 1, 2
+    # 1 => 3, 4, 5
+    # 2 => 6, 7, 8
+    LinearStrategy,
+
+    # Stepped indexing:
+    # 0 => 0, 3, 6
+    # 1 => 1, 4, 7
+    # 2 => 2, 5, 8
+    SteppedStrategy
+
   # Representing a strategy for grouping indices (of blocks usually)
   # Given an interation-count as input, will produce a seq of
   # selected indices.
@@ -15,57 +26,39 @@ type
   IndexingWrongIndexError* = object of IndexingError
   IndexingWrongIterationsError* = object of IndexingError
 
-  IndexingStrategy* = ref object of RootObj
+  IndexingStrategy* = object
+    strategyType*: StrategyType
     firstIndex*: int             # Lowest index that can be returned
     lastIndex*: int              # Highest index that can be returned
-    numberOfIterations*: int     # getIndices(iteration) will run from 0 ..< numberOfIterations
+    iterations*: int             # getIndices(iteration) will run from 0 ..< iterations
     step*: int
 
-  # Simplest approach:
-  # 0 => 0, 1, 2
-  # 1 => 3, 4, 5
-  # 2 => 6, 7, 8
-  LinearIndexingStrategy* = ref object of IndexingStrategy
-
-  # Stepped indexing:
-  # 0 => 0, 3, 6
-  # 1 => 1, 4, 7
-  # 2 => 2, 5, 8
-  SteppedIndexingStrategy* = ref object of IndexingStrategy
-
-proc checkIteration(
-  self: IndexingStrategy,
-  iteration: int): void {.raises: [IndexingError].} =
-  if iteration >= self.numberOfIterations:
+func checkIteration(self: IndexingStrategy, iteration: int): void {.raises: [IndexingError].} =
+  if iteration >= self.iterations:
     raise newException(
       IndexingError,
-      "Indexing iteration can't be greater than or equal to numberOfIterations.")
-
-method getIndicies*(
-  self: IndexingStrategy,
-  iteration: int): Iter[int] {.base, raises: [IndexingError].} =
-  raiseAssert("Not implemented")
+      "Indexing iteration can't be greater than or equal to iterations.")
 
 proc getIter(first, last, step: int): Iter[int] =
   var
     finish = false
     cur = first
-  proc get(): int =
+
+  func get(): int =
     result = cur
     cur += step
 
     if cur > last:
       finish = true
 
-  proc isFinished(): bool =
+  func isFinished(): bool =
     finish
 
   Iter.new(get, isFinished)
 
-method getIndicies*(
-  self: LinearIndexingStrategy,
+func getLinearIndicies(
+  self: IndexingStrategy,
   iteration: int): Iter[int] {.raises: [IndexingError].} =
-
   self.checkIteration(iteration)
 
   let
@@ -74,33 +67,44 @@ method getIndicies*(
 
   getIter(first, last, 1)
 
-method getIndicies*(
-  self: SteppedIndexingStrategy,
+func getSteppedIndicies(
+  self: IndexingStrategy,
   iteration: int): Iter[int] {.raises: [IndexingError].} =
-
   self.checkIteration(iteration)
 
   let
     first = self.firstIndex + iteration
     last = self.lastIndex
 
-  getIter(first, last, self.numberOfIterations)
+  getIter(first, last, self.iterations)
+
+func getIndicies*(
+  self: IndexingStrategy,
+  iteration: int): Iter[int] {.raises: [IndexingError].} =
+
+  case self.strategyType
+  of StrategyType.LinearStrategy:
+    self.getLinearIndicies(iteration)
+  of StrategyType.SteppedStrategy:
+    self.getSteppedIndicies(iteration)
+
+func init*(
+  strategy: StrategyType,
+  firstIndex, lastIndex, iterations: int): IndexingStrategy {.raises: [IndexingError].} =
 
-proc new*(
-  T: type IndexingStrategy,
-  firstIndex, lastIndex, numberOfIterations: int): T {.raises: [IndexingError].} =
   if firstIndex > lastIndex:
     raise newException(
       IndexingWrongIndexError,
       "firstIndex (" & $firstIndex & ") can't be greater than lastIndex (" & $lastIndex & ")")
 
-  if numberOfIterations <= 0:
+  if iterations <= 0:
     raise newException(
       IndexingWrongIterationsError,
-      "numberOfIteration (" & $numberOfIterations & ") must be greater than zero.")
+      "iterations (" & $iterations & ") must be greater than zero.")
 
-  T(
+  IndexingStrategy(
+    strategyType: strategy,
     firstIndex: firstIndex,
     lastIndex: lastIndex,
-    numberOfIterations: numberOfIterations,
-    step: divUp((lastIndex - firstIndex), numberOfIterations))
+    iterations: iterations,
+    step: divUp((lastIndex - firstIndex), iterations))

codex/slots/builder/builder.nim

@@ -341,7 +341,7 @@ proc new*(
 
   let
     strategy = if strategy.isNone:
-      ? SteppedIndexingStrategy.new(
+      ? SteppedStrategy.init(
         0, manifest.blocksCount - 1, manifest.numSlots).catch
       else:
         strategy.get

codex/utils/asynciter.nim

@@ -4,9 +4,9 @@ import pkg/questionable
 import pkg/chronos
 
 type
-  Function*[T, U] = proc(fut: T): U {.raises: [CatchableError], gcsafe, closure.}
-  IsFinished* = proc(): bool {.raises: [], gcsafe, closure.}
-  GenNext*[T] = proc(): T {.raises: [CatchableError], gcsafe, closure.}
+  Function*[T, U] = proc(fut: T): U {.raises: [CatchableError], gcsafe, noSideEffect.}
+  IsFinished* = proc(): bool {.raises: [], gcsafe, noSideEffect.}
+  GenNext*[T] = proc(): T {.raises: [CatchableError], gcsafe.}
   Iter*[T] = ref object
     finished: bool
     next*: GenNext[T]

tests/codex/slots/provingtestenv.nim

@@ -83,7 +83,7 @@ proc createSlotTree(self: ProvingTestEnvironment, dSlotIndex: uint64): Future[Po
   let
     slotSize = (bytesPerBlock * numberOfSlotBlocks).uint64
     blocksInSlot = slotSize div bytesPerBlock.uint64
-    datasetBlockIndexingStrategy = SteppedIndexingStrategy.new(0, self.datasetBlocks.len - 1, totalNumberOfSlots)
+    datasetBlockIndexingStrategy = SteppedStrategy.init(0, self.datasetBlocks.len - 1, totalNumberOfSlots)
     datasetBlockIndices = toSeq(datasetBlockIndexingStrategy.getIndicies(dSlotIndex.int))
 
   let

tests/codex/slots/testslotbuilder.nim

@@ -201,7 +201,7 @@ suite "Slot builder":
 
   test "Should build slot hashes for all slots":
     let
-      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      steppedStrategy = SteppedStrategy.init(0, numTotalBlocks - 1, numSlots)
       slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
@@ -224,7 +224,7 @@ suite "Slot builder":
 
   test "Should build slot trees for all slots":
     let
-      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      steppedStrategy = SteppedStrategy.init(0, numTotalBlocks - 1, numSlots)
       slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
@@ -272,7 +272,7 @@ suite "Slot builder":
 
   test "Should build correct verification root":
     let
-      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      steppedStrategy = SteppedStrategy.init(0, numTotalBlocks - 1, numSlots)
       slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,
@@ -301,7 +301,7 @@ suite "Slot builder":
 
   test "Should build correct verification root manifest":
     let
-      steppedStrategy = SteppedIndexingStrategy.new(0, numTotalBlocks - 1, numSlots)
+      steppedStrategy = SteppedStrategy.init(0, numTotalBlocks - 1, numSlots)
       slotBuilder = SlotsBuilder.new(
         localStore,
         protectedManifest,

tests/codex/testindexingstrategy.nim

@@ -14,8 +14,8 @@ for offset in @[0, 1, 2, 100]:
       firstIndex = 0 + offset
       lastIndex = 12 + offset
       nIters = 3
-      linear = LinearIndexingStrategy.new(firstIndex, lastIndex, nIters)
-      stepped = SteppedIndexingStrategy.new(firstIndex, lastIndex, nIters)
+      linear = LinearStrategy.init(firstIndex, lastIndex, nIters)
+      stepped = SteppedStrategy.init(firstIndex, lastIndex, nIters)
 
     test "linear":
       check:
@@ -31,32 +31,32 @@ for offset in @[0, 1, 2, 100]:
 
 suite "Indexing strategies":
   let
-    linear = LinearIndexingStrategy.new(0, 10, 3)
-    stepped = SteppedIndexingStrategy.new(0, 10, 3)
+    linear = LinearStrategy.init(0, 10, 3)
+    stepped = SteppedStrategy.init(0, 10, 3)
 
   test "smallest range 0":
     let
-      l = LinearIndexingStrategy.new(0, 0, 1)
-      s = SteppedIndexingStrategy.new(0, 0, 1)
+      l = LinearStrategy.init(0, 0, 1)
+      s = SteppedStrategy.init(0, 0, 1)
     check:
       toSeq(l.getIndicies(0)) == @[0]
       toSeq(s.getIndicies(0)) == @[0]
 
   test "smallest range 1":
     let
-      l = LinearIndexingStrategy.new(0, 1, 1)
-      s = SteppedIndexingStrategy.new(0, 1, 1)
+      l = LinearStrategy.init(0, 1, 1)
+      s = SteppedStrategy.init(0, 1, 1)
     check:
       toSeq(l.getIndicies(0)) == @[0, 1]
       toSeq(s.getIndicies(0)) == @[0, 1]
 
   test "first index must be smaller than last index":
     expect IndexingWrongIndexError:
-      discard LinearIndexingStrategy.new(10, 0, 1)
+      discard LinearStrategy.init(10, 0, 1)
 
-  test "numberOfIterations must be greater than zero":
+  test "iterations must be greater than zero":
     expect IndexingWrongIterationsError:
-      discard LinearIndexingStrategy.new(0, 10, 0)
+      discard LinearStrategy.init(0, 10, 0)
 
   test "linear - oob":
     expect IndexingError: