Merge branch 'main' into linking-prs

CONTRIBUTING.md

@@ -102,13 +102,17 @@ The `internal` subpackages contain most of the FerretDB code:
 * `clientconn` package provides client connection implementation.
   It accepts client connections, reads `wire`/`bson` protocol messages, and passes them to `handlers`.
   Responses are then converted to `wire`/`bson` messages and sent back to the client.
-* `handlers` handle protocol commands.
-  They use `fjson` package for storing data in PostgreSQL in jsonb columns, but they don't use `bson` package –
-  all data is represented as built-in and `types` types.
+* `handlers` contains a common interface for backend handlers that they should implement.
+  Handlers use `types` and `wire` packages, but `bson` package details are hidden.
+* `handlers/common` contains code shared by different handlers.
+* `handlers/dummy` contains a stub implementation of that interface that could be copied into a new package
+  as a starting point for the new handlers.
+* `handlers/pg` contains the implementation of the PostgreSQL handler.
 * `handlers/pg/pjson` provides converters from/to PJSON for built-in and `types` types.
   PJSON adds some extensions to JSON for keeping object keys in order,
   preserving BSON type information in the values themselves, etc.
   It is used by `pg` handler.
+* `handlers/tigris` contains the implementation of the Tigris handler.
 * `tjson` provides converters from/to JSON with JSON Schema for built-in and `types` types.
   BSON type information is preserved either in the schema (where possible) or in the values themselves.
   It is used by `tigris` handler.

internal/handlers/dummy/dummy.go

@@ -33,8 +33,11 @@ func notImplemented(command string) error {
 //   - connectionStatus;
 //   - debugError;
 //   - getCmdLineOpts;
+//   - getFreeMonitoringStatus;
 //   - hostInfo;
-//   - listCommands.
+//   - listCommands;
+//   - setFreeMonitoringStatus;
+//   - whatsmyuri.
 type Handler struct{}
 
 // New returns a new handler.

internal/handlers/tigris/msg_collmod.go

@@ -17,11 +17,11 @@ package tigris
 import (
 	"context"
 
-	"github.com/FerretDB/FerretDB/internal/util/must"
+	"github.com/FerretDB/FerretDB/internal/handlers/common"
 	"github.com/FerretDB/FerretDB/internal/wire"
 )
 
 // MsgCollMod implements HandlerInterface.
 func (h *Handler) MsgCollMod(ctx context.Context, msg *wire.OpMsg) (*wire.OpMsg, error) {
-	return nil, notImplemented(must.NotFail(msg.Document()).Command())
+	return nil, common.NewErrorMsg(common.ErrNotImplemented, "`collMod` command is not implemented yet")
 }

internal/handlers/tigris/msg_explain.go

@@ -17,11 +17,11 @@ package tigris
 import (
 	"context"
 
-	"github.com/FerretDB/FerretDB/internal/util/must"
+	"github.com/FerretDB/FerretDB/internal/handlers/common"
 	"github.com/FerretDB/FerretDB/internal/wire"
 )
 
 // MsgExplain implements HandlerInterface.
 func (h *Handler) MsgExplain(ctx context.Context, msg *wire.OpMsg) (*wire.OpMsg, error) {
-	return nil, notImplemented(must.NotFail(msg.Document()).Command())
+	return nil, common.NewErrorMsg(common.ErrNotImplemented, "`explain` command is not implemented yet")
 }

internal/handlers/tigris/tigris.go

@@ -30,11 +30,6 @@ import (
 	"github.com/FerretDB/FerretDB/internal/util/lazyerrors"
 )
 
-// notImplemented returns error for stub command handlers.
-func notImplemented(command string) error {
-	return common.NewErrorMsg(common.ErrNotImplemented, "I'm a stub, not a real handler for "+command)
-}
-
 // NewOpts represents handler configuration.
 type NewOpts struct {
 	ClientID     string