[#1103] node: Implement Get\Head requests for EC object

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

pkg/services/object/get/assembleec.go

@@ -0,0 +1,79 @@
+package getsvc
+
+import (
+	"context"
+	"errors"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
+	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
+	"go.uber.org/zap"
+)
+
+func (r *request) assembleEC(ctx context.Context) {
+	if r.isRaw() {
+		r.log.Debug(logs.GetCanNotAssembleTheObject)
+		return
+	}
+
+	// Any access tokens are not expected to be used in the assembly process:
+	//  - there is no requirement to specify child objects in session/bearer
+	//    token for `GET`/`GETRANGE`/`RANGEHASH` requests in the API protocol,
+	//    and, therefore, their missing in the original request should not be
+	//    considered as error; on the other hand, without session for every child
+	//    object, it is impossible to attach bearer token in the new generated
+	//    requests correctly because the token has not been issued for that node's
+	//    key;
+	//  - the assembly process is expected to be handled on a container node
+	//    only since the requests forwarding mechanism presentation; such the
+	//    node should have enough rights for getting any child object by design.
+	r.prm.common.ForgetTokens()
+
+	// Do not use forwarding during assembly stage.
+	// Request forwarding closure inherited in produced
+	// `execCtx` so it should be disabled there.
+	r.disableForwarding()
+
+	r.log.Debug(logs.GetTryingToAssembleTheECObject)
+
+	assembler := newAssemblerEC(r.address(), r.infoEC, r.ctxRange(), r, r.containerSource, r.log)
+
+	r.log.Debug(logs.GetAssemblingECObject,
+		zap.Stringer("address", r.address()),
+		zap.Uint64("range_offset", r.ctxRange().GetOffset()),
+		zap.Uint64("range_length", r.ctxRange().GetLength()),
+	)
+	defer r.log.Debug(logs.GetAssemblingECObjectCompleted,
+		zap.Stringer("address", r.address()),
+		zap.Uint64("range_offset", r.ctxRange().GetOffset()),
+		zap.Uint64("range_length", r.ctxRange().GetLength()),
+	)
+
+	obj, err := assembler.Assemble(ctx, r.prm.objWriter, r.headOnly())
+	if err != nil {
+		r.log.Warn(logs.GetFailedToAssembleECObject,
+			zap.Error(err),
+			zap.Stringer("address", r.address()),
+			zap.Uint64("range_offset", r.ctxRange().GetOffset()),
+			zap.Uint64("range_length", r.ctxRange().GetLength()),
+		)
+	}
+
+	var errRemoved *apistatus.ObjectAlreadyRemoved
+	var errOutOfRange *apistatus.ObjectOutOfRange
+
+	switch {
+	default:
+		r.status = statusUndefined
+		r.err = err
+	case err == nil:
+		r.status = statusOK
+		r.err = nil
+		r.collectedObject = obj
+	case errors.As(err, &errRemoved):
+		r.status = statusINHUMED
+		r.err = errRemoved
+	case errors.As(err, &errOutOfRange):
+		r.status = statusOutOfRange
+		r.err = errOutOfRange
+	}
+}