Add ErrorConfig to hold errors contacting locations.

protocol/src/main/protobuf/raw/protocol/protocol.proto

@@ -23,6 +23,7 @@ message LocationConfig {
         DropboxUsernamePasswordConfig dropboxUsernamePassword = 14;
         HttpHeadersConfig httpHeaders = 15;
         SecretConfig secret = 99;
+        ErrorConfig error = 9999;
     }
 }
 
@@ -145,4 +146,8 @@ message HttpHeadersConfig {
 message SecretConfig {
     string name = 1;
     string value = 2;
+}
+
+message ErrorConfig {
+    string message = 1;
 }

snapi-frontend/src/main/scala/raw/compiler/rql2/api/LocationDescription.scala

@@ -574,7 +574,7 @@ object LocationDescription extends StrictLogging {
             val delay = parser.getDuration("delay").toMillis
             urlToLocationDescription(delegateUri, programEnvironment).right.map(MockPathLocationDescription(delay, _))
           } catch {
-            case _: ConfigException => Left(s"not a mock location: $url")
+            case _: ConfigException => Left("not a mock location")
           }
         }
       case "s3" =>
@@ -624,6 +624,8 @@ object LocationDescription extends StrictLogging {
                   objectKey
                 )
               )
+            case Some(l) if l.hasError => Left(l.getError.getMessage)
+            case Some(_) => Left("not a S3 credential")
             case None =>
               // Anonymous access.
               Right(S3PathLocationDescription(bucketName, None, None, None, objectKey))
@@ -636,6 +638,7 @@ object LocationDescription extends StrictLogging {
         // In Dropbox, the host is the name of the credential
         val DROPBOX_REGEX(name, path) = url
         if (name == null) {
+          logger.warn("missing 'name' in Dropbox location")
           return Left("missing Dropbox credential")
         }
         programEnvironment.locationConfigs.get(name) match {
@@ -651,7 +654,28 @@ object LocationDescription extends StrictLogging {
                 path
               )
             )
-          case None => Left("missing Dropbox credential")
+          case Some(l) if l.hasHttpHeaders =>
+            if (l.getHttpHeaders.getHeadersMap.containsKey("Authorization")) {
+              val splitted = l.getHttpHeaders.getHeadersMap.get("Authorization").split("Bearer ")
+              if (splitted.length == 2) {
+                Right(
+                  DropboxAccessTokenLocationDescription(
+                    splitted(1),
+                    path
+                  )
+                )
+              } else {
+                Left("invalid Dropbox credential")
+              }
+            } else {
+              logger.warn("missing Dropbox 'Authorization'")
+              Left("missing Dropbox credential")
+            }
+          case Some(l) if l.hasError => Left(l.getError.getMessage)
+          case Some(_) => Left("not a Dropbox credential")
+          case None =>
+            logger.warn("missing Dropbox credential")
+            Left("missing Dropbox credential")
         }
       case _ => Left(s"unsupported protocol: $protocol")
     }

snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/MySQLPackage.scala

@@ -150,6 +150,7 @@ class MySQLInferAndReadEntry extends SugarEntryExtension {
             new MySqlTableLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword, table)(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a MySQL server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -394,6 +395,7 @@ class MySQLInferAndQueryEntry extends SugarEntryExtension {
             new MySqlServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a MySQL server")
           case None => return Left(s"unknown credential: $db")
         }

snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/OraclePackage.scala

@@ -170,6 +170,7 @@ class OracleInferAndReadEntry extends SugarEntryExtension {
             new OracleTableLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword, schema, table)(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -423,6 +424,7 @@ class OracleInferAndQueryEntry extends SugarEntryExtension {
             new OracleServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }

snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/PostgreSQLPackage.scala

@@ -178,6 +178,7 @@ class PostgreSQLInferAndReadEntry extends SugarEntryExtension {
             )(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a PostgreSQL server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -433,6 +434,7 @@ class PostgreSQLInferAndQueryEntry extends SugarEntryExtension {
             new PostgresqlServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }

snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SQLServerPackage.scala

@@ -179,6 +179,7 @@ class SQLServerInferAndReadEntry extends SugarEntryExtension {
             )(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -435,6 +436,7 @@ class SQLServerInferAndQueryEntry extends SugarEntryExtension {
             new SqlServerServerLocation(l1.getHost, l1.getPort, l1.getDatabase, l1.getUser, l1.getPassword)(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not an Oracle server")
           case None => return Left(s"unknown credential: $db")
         }

snapi-frontend/src/main/scala/raw/compiler/rql2/builtin/SnowflakePackage.scala

@@ -211,6 +211,7 @@ class SnowflakeInferAndReadEntry extends SugarEntryExtension {
             )(
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a Snowflake server")
           case None => return Left(s"unknown credential: $db")
         }
@@ -501,6 +502,7 @@ class SnowflakeInferAndQueryEntry extends SugarEntryExtension {
               l1.getParametersMap,
               programContext.settings
             )
+          case Some(l) if l.hasError => return Left(l.getError.getMessage)
           case Some(_) => return Left("not a Snowflake server")
           case None => return Left(s"unknown credential: $db")
         }

snapi-truffle/src/main/java/raw/runtime/truffle/RawContext.java

@@ -123,7 +123,11 @@ public LocationConfig getLocationConfig(String name) {
     if (maybeLocationConfig.isEmpty()) {
       throw new RawTruffleRuntimeException("unknown credential: " + name);
     }
-    return maybeLocationConfig.get();
+    LocationConfig locationConfig = maybeLocationConfig.get();
+    if (locationConfig.hasError()) {
+      throw new RawTruffleRuntimeException(locationConfig.getError().getMessage());
+    }
+    return locationConfig;
   }
 
   @CompilerDirectives.TruffleBoundary

sql-client/src/main/scala/raw/client/sql/SqlConnection.scala

@@ -33,11 +33,18 @@ import java.util.concurrent.Executor
 class SqlConnection(connectionPool: SqlConnectionPool, conn: Connection) extends java.sql.Connection {
 
   override def close(): Unit = {
-    // We do not ACTUALLY close the connection; instead, we just release the borrow.
-    connectionPool.releaseConnection(
-      this,
-      isAlive = false //  We are not sure if the connection is alive or not, e.g. it could be closed because it failed.
-    )
+    if (isClosed) {
+      // If the connection closed in the meantime (e.g. due to a crash), we cannot release it back to the pool.
+      connectionPool.actuallyRemoveConnection(this)
+    } else {
+      // If the connection seems "sane", then we do not ACTUALLY close the connection.
+      // Instead, we just release the borrow.
+      connectionPool.releaseConnection(
+        this,
+        isAlive =
+          false //  We are not sure if the connection is alive or not, e.g. it could be closed because it failed.
+      )
+    }
   }
 
   // This is called by the connection pool when we *actually* want to close the connection.

sql-client/src/main/scala/raw/client/sql/SqlConnectionPool.scala

@@ -90,7 +90,7 @@ class SqlConnectionPool()(implicit settings: RawSettings) extends RawService wit
           logger.debug(s"Checking the connection health for $conn (state: ${connectionUrls(conn)})")
           // Found one connection to check.
           try {
-            if (conn.isValid(isValidSeconds)) {
+            if (!conn.isClosed() && conn.isValid(isValidSeconds)) {
               logger.debug(s"Connection $conn is healthy")
               // All good, so release borrow.
               // This will update the last check is alive time.
@@ -225,27 +225,32 @@ class SqlConnectionPool()(implicit settings: RawSettings) extends RawService wit
     }
   }
 
-  private def actuallyRemoveConnection(conn: SqlConnection): Boolean = {
-    logger.debug(s"Actually removing connection $conn")
+  def actuallyRemoveConnection(conn: SqlConnection): Boolean = {
     connectionPoolLock.synchronized {
-      val jdbcUrl = connectionUrls(conn)
-      try {
-        // First try to actually close the connection (note the use of actuallyClose), then clean up all the state.
-        conn.actuallyClose()
-        connectionState.remove(conn)
-        connectionUrls.remove(conn)
-        connectionCache.get(jdbcUrl) match {
-          case Some(conns) =>
-            val nconns = conns - conn
-            if (nconns.isEmpty) connectionCache.remove(jdbcUrl)
-            else connectionCache.put(jdbcUrl, nconns)
-          case None => // Nothing to do.
-        }
-        true
-      } catch {
-        case NonFatal(t) =>
-          // We failed to actually close the connection.
-          logger.warn(s"Failed to actually close the connection $conn", t)
+      connectionUrls.get(conn) match {
+        case Some(jdbcUrl) =>
+          logger.debug(s"Actually removing connection $conn")
+          try {
+            // First try to actually close the connection (note the use of actuallyClose), then clean up all the state.
+            conn.actuallyClose()
+            connectionState.remove(conn)
+            connectionUrls.remove(conn)
+            connectionCache.get(jdbcUrl) match {
+              case Some(conns) =>
+                val nconns = conns - conn
+                if (nconns.isEmpty) connectionCache.remove(jdbcUrl)
+                else connectionCache.put(jdbcUrl, nconns)
+              case None => // Nothing to do.
+            }
+            true
+          } catch {
+            case NonFatal(t) =>
+              // We failed to actually close the connection.
+              logger.warn(s"Failed to actually close the connection $conn", t)
+              false
+          }
+        case None =>
+          // Connection didn't exist/was removed already.
           false
       }
     }