feat(CosmosStore): Expose ISyncContext.SessionToken

CHANGELOG.md

@@ -11,6 +11,7 @@ The `Unreleased` section name is replaced by the expected version of next releas
 ### Added
 
 - now targets `Microsoft.Azure.Cosmos` v `3.1.1` (instead of `Microsoft.Azure.DocumentDB`[`.Core`] v 2.x) [#144](https://github.com/jet/equinox/pull/144)
+- `Core.ISyncContext.SessionToken`: Allows one to inspect the `SessionToken` for relevant stores (i.e., `CosmosDB`), after loading and/or syncing has concluded [#195](https://github.com/jet/equinox/pull/195) 
 
 ### Changed
 

src/Equinox.Cosmos/Cosmos.fs

@@ -752,8 +752,9 @@ module internal Tip =
 type [<NoComparison>] Token = { container: Container; stream: string; pos: Position }
 module Token =
     let create (container,stream) pos : StreamToken =
-        {  value = box { container = container; stream = stream; pos = pos }
-           version = pos.index }
+        {   value = box { container = container; stream = stream; pos = pos }
+            version = pos.index
+            sessionToken = null }
     let (|Unpack|) (token: StreamToken) : Container*string*Position = let t = unbox<Token> token.value in t.container,t.stream,t.pos
     let supersedes (Unpack (_,_,currentPos)) (Unpack (_,_,xPos)) =
         let currentVersion, newVersion = currentPos.index, xPos.index

src/Equinox.Cosmos/Equinox.Cosmos.fsproj

@@ -19,7 +19,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="1.1.0" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
     <PackageReference Include="MinVer" Version="2.0.0" PrivateAssets="All" />
 

src/Equinox.EventStore/EventStore.fs

@@ -317,7 +317,8 @@ module Token =
         {   value = box {
                 stream = { name = streamName}
                 pos = { streamVersion = streamVersion; compactionEventNumber = compactionEventNumber; batchCapacityLimit = batchCapacityLimit } }
-            version = streamVersion }
+            version = streamVersion
+            sessionToken = null }
 
     /// No batching / compaction; we only need to retain the StreamVersion
     let ofNonCompacting streamName streamVersion : StreamToken =

src/Equinox.MemoryStore/MemoryStore.fs

@@ -45,7 +45,8 @@ module private Token =
 
     let private streamTokenOfIndex streamName (streamVersion : int) : StreamToken =
         {   value = box { streamName = streamName; streamVersion = streamVersion }
-            version = int64 streamVersion }
+            version = int64 streamVersion
+            sessionToken = null }
     let (|Unpack|) (token: StreamToken) : Token = unbox<Token> token.value
     /// Represent a stream known to be empty
     let ofEmpty streamName initial = streamTokenOfIndex streamName -1, initial

src/Equinox.SqlStreamStore/SqlStreamStore.fs

@@ -298,7 +298,8 @@ module Token =
         {   value = box {
                 stream = { name = streamName}
                 pos = { streamVersion = streamVersion; compactionEventNumber = compactionEventNumber; batchCapacityLimit = batchCapacityLimit } }
-            version = streamVersion }
+            version = streamVersion
+            sessionToken = null }
     /// No batching / compaction; we only need to retain the StreamVersion
     let ofNonCompacting streamName streamVersion : StreamToken =
         create None None streamName streamVersion

src/Equinox/Flow.fs

@@ -6,7 +6,7 @@ open Serilog
 
 /// Store-specific opaque token to be used for synchronization purposes
 [<NoComparison>]
-type StreamToken = { value : obj; version: int64 }
+type StreamToken = { value : obj; version: int64; sessionToken : string }
 
 /// Internal type used to represent the outcome of a TrySync operation
 [<NoEquality; NoComparison; RequireQualifiedAccess>]
@@ -36,6 +36,10 @@ type ISyncContext<'state> =
     /// Exposes the underlying Store's internal Version/Index (which, depending on the Codec, may or may not be reflected in the last event presented)
     abstract member Version : int64
 
+    /// Exposes the underlying Store's internal SessionToken
+    // (relevant to CosmosDB)
+    abstract member SessionToken : string
+
     /// The present State of the stream within the context of this Flow
     abstract member State : 'state
 
@@ -61,6 +65,7 @@ module internal Flow =
             member __.CreateMemento() = tokenAndState
             member __.State = snd tokenAndState
             member __.Version = (fst tokenAndState).version
+            member __.SessionToken = (fst tokenAndState).sessionToken
 
         member __.TryWithoutResync(log : ILogger, events) : Async<bool> =
             trySyncOr log events (fun _resync -> async { return false })