From 0b4aa893111f82020cba8f3d965b3ce5c7e52913 Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Tue, 4 Jun 2024 12:24:20 +0300
Subject: [PATCH] postgre-actor: convert to gatekeeper protocol

---
 README.md             | 49 +++++++++++----------
 config.prs            |  6 +--
 src/postgre_actor.nim | 99 +++++++++++++++++++++++--------------------
 src/schema/config.nim | 33 +++++++--------
 src/syndesizer.nim    | 20 ++++-----
 5 files changed, 106 insertions(+), 101 deletions(-)

diff --git a/README.md b/README.md
index 3d7b68d..53be6f5 100644
--- a/README.md
+++ b/README.md
@@ -374,34 +374,37 @@ When called as `assert` (by a symlink or a rename) it will make assertions inste
 
 ## PostgreSQL
 
-Readonly access to PostgreSQL databases. Asserts rows as records in response to SQL query assertions. Dynamic updates are not implemented.
-
-Can be disabled by passing `--define:withPostgre=no` to the Nim compiler.
+Readonly access to PostgreSQL databases.
+Asserts rows as records in response to SQL query assertions.
+Dynamic updates are not implemented.
 
 ```
-# Configuration example
-<require-service <daemon postgre_actor>>
-
-let ?sqlspace = dataspace
-
-? <service-object <daemon postgre_actor> ?cap> [
-  $cap <postgre {
-     dataspace: $sqlspace
-     connection: [
-       ["host" "example.com"]
-       ["dbname" "foobar"]
-       ["user" "hackme"]
-     ]
-   }>
-]
+let ?postgreStep = <postgre {connection: [["host" "db.example.com"] ["dbname" "example"] ["user" "hackme"]]}>
 
 let ?tuplespace = dataspace
-
-$sqlspace <query "SELECT id, name FROM stuff" $tuplespace>
-
-$tuplespace ? [?id ?name] [
-  $log ! <log "-" { row: <example-row $id $name> }>
+$tuplespace ? ?row [
+  $log ! <log "-" { line: $row }>
 ]
+
+let ?resolver = dataspace
+$resolver ? <accepted ?sqlspace> [
+  $sqlspace ? <sql-error ?msg ?context> [
+    $log ! <log "-" { line: $msg context: $context }>
+  ]
+  $sqlspace <query [SELECT firstname FROM users] $tuplespace>
+]
+
+<require-service <daemon postgre-actor>>
+$config ? <service-object <daemon postgre-actor> ?cap> [
+  $cap <resolve $postgreStep $resolver>
+]
+
+<daemon postgre-actor {
+  argv: [ "/bin/postgre-actor" ]
+  clearEnv: #t
+  protocol: application/syndicate
+}>
+
 ```
 
 ## preserve_process_environment
diff --git a/config.prs b/config.prs
index 1dd9f05..9922c1a 100644
--- a/config.prs
+++ b/config.prs
@@ -36,9 +36,8 @@ JsonSocketTranslatorStep = <json-socket-translator {
   socket: SocketAddress
 }>.
 
-PostgreArguments = <postgre {
+PostgreStep = <postgre {
   connection: [PostgreConnectionParameter ...]
-  dataspace: #:any
 }>.
 PostgreConnectionParameter = [@key string @val string].
 
@@ -48,9 +47,8 @@ PulseArguments = <pulse {
   dataspace: #:any
 }>.
 
-SqliteArguments = <sqlite {
+SqliteStep = <sqlite {
   database: string
-  dataspace: #:any
 }>.
 
 WebhooksArguments = <webhooks {
diff --git a/src/postgre_actor.nim b/src/postgre_actor.nim
index 63864cd..bafcc15 100644
--- a/src/postgre_actor.nim
+++ b/src/postgre_actor.nim
@@ -1,8 +1,10 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense
 
-import preserves, syndicate
-import ./schema/[config, sql]
+import
+  pkg/preserves,
+  pkg/syndicate, pkg/syndicate/protocols/[gatekeeper, sturdy],
+  ./schema/[config, sql]
 
 {.passL: "-lpq".}
 
@@ -105,54 +107,57 @@ proc renderSql(tokens: openarray[Value]): string =
     else:
       return ""
 
-proc spawnPostgreActor*(turn: Turn; root: Cap): Actor {.discardable.} =
-  spawn("postgre", turn) do (turn: Turn):
-    during(turn, root, ?:PostgreArguments) do (params: StringPairs, ds: Cap):
-      var
-        conn: PGconn
-        statusHandle: Handle
-        (keys, vals) = splitParams(params)
-      conn = PQconnectdbParams(keys, vals, 0)
-      checkPointer(conn)
-      let
-        status = PQstatus(conn)
-        msg = $PQerrorMessage(conn)
-      statusHandle = publish(turn, ds,
-          initRecord("status", toSymbol($status), msg.toPreserves))
-      if status == CONNECTION_OK:
-        during(turn, ds, ?:Query) do (statement: seq[Value], target: Cap):
-          var text = renderSql statement
-          if text == "":
-            discard publish(turn, ds, SqlError(msg: "invalid statement", context: $statement))
-          else:
-            var
-              res = PQexec(conn, text)
-              st = PQresultStatus(res)
-            if st == PGRES_TUPLES_OK or st == PGRES_SINGLE_TUPLE:
-              let tuples = PQntuples(res)
-              let fields = PQnfields(res)
-              if tuples > 0 and fields > 0:
-                for r in 0..<tuples:
-                  var tupl = initSequence(fields)
-                  for f in 0..<fields:
-                    tupl[f] = toPreserves($PQgetvalue(res, r, f))
-                  discard publish(turn, target, tupl)
+proc spawnPostgreActor*(turn: Turn; relay: Cap): Actor {.discardable.} =
+  result = spawnActor(turn, "postgre") do (turn: Turn):
+    let pat = Resolve?:{ 0: PostgreStep.grabTypeFlat, 1: grab() }
+    during(turn, relay, pat) do (params: StringPairs, observer: Cap):
+      linkActor(turn, path) do (turn: Turn):
+        var
+          (keys, vals) = splitParams(params)
+          conn = PQconnectdbParams(keys, vals, 0)
+        checkPointer(conn)
+        let
+          status = PQstatus(conn)
+          msg = $PQerrorMessage(conn)
+        deallocCStringArray(keys)
+        deallocCStringArray(vals)
+        onStop(turn) do (turn: Turn):
+          PQfinish(conn)
+        if status == CONNECTION_OK:
+          let ds = turn.newDataspace()
+          discard publish(turn, ds, initRecord("status", toSymbol($status), msg.toPreserves))
+          during(turn, ds, ?:Query) do (statement: seq[Value], target: Cap):
+            var text = renderSql statement
+            if text == "":
+              discard publish(turn, ds, SqlError(msg: "invalid statement", context: $statement))
             else:
-              discard publish(turn, ds, SqlError(
-                  msg: $PQresStatus(st),
-                  context: $PQresultErrorMessage(res),
-                ))
-            PQclear(res)
-      else:
-        stderr.writeLine "refusing to do anything when status is ", status
-    do:
-      deallocCStringArray(keys)
-      deallocCStringArray(vals)
-      PQfinish(conn)
+              var
+                res = PQexec(conn, text)
+                st = PQresultStatus(res)
+              if st == PGRES_TUPLES_OK or st == PGRES_SINGLE_TUPLE:
+                let tuples = PQntuples(res)
+                let fields = PQnfields(res)
+                if tuples > 0 and fields > 0:
+                  for r in 0..<tuples:
+                    var tupl = initSequence(fields)
+                    for f in 0..<fields:
+                      tupl[f] = toPreserves($PQgetvalue(res, r, f))
+                    discard publish(turn, target, tupl)
+              else:
+                discard publish(turn, ds, SqlError(
+                    msg: $PQresStatus(st),
+                    context: $PQresultErrorMessage(res),
+                  ))
+              PQclear(res)
+          discard publish(turn, observer,
+              ResolvedAccepted(responderSession: ds))
+        else:
+          discard publish(turn, observer,
+              Rejected(detail: msg.toPreserves))
 
 when isMainModule:
   import syndicate/relays
 
   runActor("main") do (turn: Turn):
-    resolveEnvironment(turn) do (turn: Turn; ds: Cap):
-      spawnPostgreActor(turn, ds)
+    resolveEnvironment(turn) do (turn: Turn; relay: Cap):
+      spawnPostgreActor(turn, relay)
diff --git a/src/schema/config.nim b/src/schema/config.nim
index 6b3d955..50583c9 100644
--- a/src/schema/config.nim
+++ b/src/schema/config.nim
@@ -78,6 +78,12 @@ type
   SqliteArguments* {.preservesRecord: "sqlite".} = object
     `field0`*: SqliteArgumentsField0
 
+  PostgreStepField0* {.preservesDictionary.} = object
+    `connection`*: seq[PostgreConnectionParameter]
+
+  PostgreStep* {.preservesRecord: "postgre".} = object
+    `field0`*: PostgreStepField0
+
   TcpAddress* {.preservesRecord: "tcp".} = object
     `host`*: string
     `port`*: BiggestInt
@@ -99,19 +105,16 @@ type
     `key`*: string
     `val`*: string
 
-  PostgreArgumentsField0* {.preservesDictionary.} = object
-    `connection`*: seq[PostgreConnectionParameter]
-    `dataspace`* {.preservesEmbedded.}: EmbeddedRef
-
-  PostgreArguments* {.preservesRecord: "postgre".} = object
-    `field0`*: PostgreArgumentsField0
-
   PulseArgumentsField0* {.preservesDictionary.} = object
     `dataspace`* {.preservesEmbedded.}: EmbeddedRef
 
   PulseArguments* {.preservesRecord: "pulse".} = object
     `field0`*: PulseArgumentsField0
 
+  Tcp* {.preservesRecord: "tcp".} = object
+    `host`*: string
+    `port`*: BiggestInt
+
   UnixAddress* {.preservesRecord: "unix".} = object
     `path`*: string
 
@@ -120,10 +123,6 @@ type
   PrinterStep* {.preservesRecord: "printer".} = object
     `field0`*: PrinterStepField0
 
-  Tcp* {.preservesRecord: "tcp".} = object
-    `host`*: string
-    `port`*: BiggestInt
-
 proc `$`*(x: WebsocketArguments | HttpClientArguments | JsonTranslatorArguments |
     SocketAddress |
     Base64DecoderArguments |
@@ -133,15 +132,15 @@ proc `$`*(x: WebsocketArguments | HttpClientArguments | JsonTranslatorArguments
     WebhooksArguments |
     FileSystemUsageArguments |
     SqliteArguments |
+    PostgreStep |
     TcpAddress |
     CacheArguments |
     XmlTranslatorArguments |
     PostgreConnectionParameter |
-    PostgreArguments |
     PulseArguments |
+    Tcp |
     UnixAddress |
-    PrinterStep |
-    Tcp): string =
+    PrinterStep): string =
   `$`(toPreserves(x))
 
 proc encode*(x: WebsocketArguments | HttpClientArguments |
@@ -154,13 +153,13 @@ proc encode*(x: WebsocketArguments | HttpClientArguments |
     WebhooksArguments |
     FileSystemUsageArguments |
     SqliteArguments |
+    PostgreStep |
     TcpAddress |
     CacheArguments |
     XmlTranslatorArguments |
     PostgreConnectionParameter |
-    PostgreArguments |
     PulseArguments |
+    Tcp |
     UnixAddress |
-    PrinterStep |
-    Tcp): seq[byte] =
+    PrinterStep): seq[byte] =
   encode(toPreserves(x))
diff --git a/src/syndesizer.nim b/src/syndesizer.nim
index d8bb104..b64e015 100644
--- a/src/syndesizer.nim
+++ b/src/syndesizer.nim
@@ -16,13 +16,13 @@ import ./syndesizer/[
   xml_translator]
 
 runActor("syndesizer") do (turn: Turn):
-  resolveEnvironment(turn) do (turn: Turn; ds: Cap):
-    discard spawnTimerDriver(turn, ds)
-    discard spawnBase64Decoder(turn, ds)
-    discard spawnCacheActor(turn, ds)
-    discard spawnFileSystemUsageActor(turn, ds)
-    discard spawnHttpDriver(turn, ds)
-    discard spawnJsonSocketTranslator(turn, ds)
-    discard spawnJsonStdioTranslator(turn, ds)
-    discard spawnPulseActor(turn, ds)
-    discard spawnXmlTranslator(turn, ds)
+  resolveEnvironment(turn) do (turn: Turn; relay: Cap):
+    discard spawnTimerDriver(turn, relay)
+    discard spawnBase64Decoder(turn, relay)
+    discard spawnCacheActor(turn, relay)
+    discard spawnFileSystemUsageActor(turn, relay)
+    discard spawnHttpDriver(turn, relay)
+    discard spawnJsonSocketTranslator(turn, relay)
+    discard spawnJsonStdioTranslator(turn, relay)
+    discard spawnPulseActor(turn, relay)
+    discard spawnXmlTranslator(turn, relay)