internal/lsp/source: limit WorkspaceSymbols results

Searching with an empty string shouldn't return every symbol in the
workspace -- nobody wants that. Limit to 100 results to avoid breaking
editors. (VS Code locks up for like 30 seconds on my workspace.)

Change-Id: I1e0be476e8eeaef9e69767bfa04a89d40bd3a6e5
Reviewed-on: https://go-review.googlesource.com/c/tools/+/220939
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/source/workspace_symbol.go

@@ -17,12 +17,15 @@ import (
 	"golang.org/x/tools/internal/telemetry/trace"
 )
 
+const maxSymbols = 100
+
 func WorkspaceSymbols(ctx context.Context, views []View, query string) ([]protocol.SymbolInformation, error) {
 	ctx, done := trace.StartSpan(ctx, "source.WorkspaceSymbols")
 	defer done()
 
 	seen := make(map[string]struct{})
 	var symbols []protocol.SymbolInformation
+outer:
 	for _, view := range views {
 		knownPkgs, err := view.Snapshot().KnownPackages(ctx)
 		if err != nil {
@@ -57,6 +60,9 @@ func WorkspaceSymbols(ctx context.Context, views []View, query string) ([]protoc
 							Range: rng,
 						},
 					})
+					if len(symbols) > maxSymbols {
+						break outer
+					}
 				}
 			}
 		}

internal/lsp/testdata/lsp/primarymod/workspacesymbol/workspacesymbol.go

@@ -1,43 +0,0 @@
-package workspacesymbol
-
-/*@
-workspacesymbol("",
-	symbolsx,
-	y,
-	Number,
-	Alias,
-	NumberAlias,
-	Boolean,
-	BoolAlias,
-	symbolsFoo,
-	fQuux,
-	W,
-	fBar,
-	baz,
-	Quux,
-	qX,
-	Y,
-	Baz,
-	qDo,
-	main,
-	Stringer,
-	String,
-	ABerInterface,
-	B,
-	ABerA,
-	WithEmbeddeds,
-	Do,
-	ABer,
-	ioWriter,
-	WorkspaceSymbolVariableA,
-	WorkspaceSymbolConstantA,
-	workspacesymbolinvariable,
-	WorkspaceSymbolVariableB,
-	WorkspaceSymbolStructB,
-	bBar,
-)
-workspacesymbol("workspacesymbolvar",
-	WorkspaceSymbolVariableA,
-	WorkspaceSymbolVariableB,
-)
-*/

internal/lsp/testdata/lsp/summary.txt.golden

@@ -19,7 +19,7 @@ ReferencesCount = 9
 RenamesCount = 23
 PrepareRenamesCount = 7
 SymbolsCount = 3
-WorkspaceSymbolsCount = 2
+WorkspaceSymbolsCount = 0
 FuzzyWorkspaceSymbolsCount = 3
 CaseSensitiveWorkspaceSymbolsCount = 2
 SignaturesCount = 23