[elastic] Move the deps download into 'intialize' request handle

The original implementation relies on 'go list' to download the deps.
'go list' is called by other request handler indirectly. This approach
is unpredictable and 'go list' is black box to us. So it's better
download the deps manually in 'ManageDeps', i.e. inside 'initialize'
request handler.

Author: Henry Wong

internal/lsp/elasticserver.go

@@ -11,6 +11,7 @@ import (
 	"golang.org/x/tools/internal/jsonrpc2"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
+	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/semver"
 	"golang.org/x/tools/internal/span"
 	"io/ioutil"
@@ -188,11 +189,9 @@ type WorkspaceFolderMeta struct {
 // manageDeps will explore the workspace folders sent from the client and give a whole picture of them. Besides that,
 // manageDeps will try its best to convert the folders to modules. The core functions, like deps downloading and deps
 // management, will be implemented in the package 'cache'.
-func (s ElasticServer) ManageDeps(folders *[]protocol.WorkspaceFolder) error {
-	// Note: For the upstream go langserver, granularity of the workspace folders is repository. But for the elastic go
-	// language server, there are repositories contain multiple modules. In order to handle the modules separately, we
-	// consider different modules as different workspace folders, so we can manage the dependency of different modules
-	// separately.
+func (s ElasticServer) ManageDeps(ctx context.Context, folders *[]protocol.WorkspaceFolder) error {
+	// In order to handle the modules separately, we consider different modules as different workspace folders, so we
+	// can manage the dependency of different modules separately.
 	for _, folder := range *folders {
 		metadata := &WorkspaceFolderMeta{}
 		if folder.URI != "" {
@@ -215,6 +214,13 @@ func (s ElasticServer) ManageDeps(folders *[]protocol.WorkspaceFolder) error {
 			}
 		}
 	}
+	for _, folder := range *folders {
+		cmd := exec.Command("go", "mod", "download")
+		cmd.Dir = span.NewURI(folder.URI).Filename()
+		if err := cmd.Run(); err != nil {
+			log.Error(ctx, "failed to download the dependencies", err)
+		}
+	}
 	return nil
 }
 

internal/lsp/protocol/elasticserver.go

@@ -11,7 +11,7 @@ type ElasticServer interface {
 	Server
 	EDefinition(context.Context, *TextDocumentPositionParams) ([]SymbolLocator, error)
 	Full(context.Context, *FullParams) (FullResponse, error)
-	ManageDeps(folders *[]WorkspaceFolder) error
+	ManageDeps(context.Context, *[]WorkspaceFolder) error
 }
 
 type elasticServerHandler struct {
@@ -39,7 +39,7 @@ func (h elasticServerHandler) Deliver(ctx context.Context, r *jsonrpc2.Request,
 			sendParseError(ctx, r, err)
 			return true
 		}
-		if err := h.server.ManageDeps(&params.Event.Added); err != nil {
+		if err := h.server.ManageDeps(ctx, &params.Event.Added); err != nil {
 			log.Error(ctx, "", err)
 		}
 		if err := h.server.DidChangeWorkspaceFolders(ctx, &params); err != nil {
@@ -223,7 +223,7 @@ func (h elasticServerHandler) Deliver(ctx context.Context, r *jsonrpc2.Request,
 			sendParseError(ctx, r, err)
 			return true
 		}
-		if err := h.server.ManageDeps(&params.WorkspaceFolders); err != nil {
+		if err := h.server.ManageDeps(ctx, &params.WorkspaceFolders); err != nil {
 			log.Error(ctx, "", err)
 		}
 		resp, err := h.server.Initialize(ctx, &params)