[feature/performance] Fail fast when doing remote transport calls inside incoming request contexts (#1119)

* [feature/performance] Fail fast when doing remote transport calls inside incoming request contexts

* [chore] Reduce outgoing request timeout to 15s

* log error messages when fastfailing

* use context.Value() instead of wrapped context, wrap error with fastfail instead of extra log entry

* add fast-fail context key test

Signed-off-by: kim <grufwub@gmail.com>
Co-authored-by: kim <grufwub@gmail.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/internal/transport/context.go b/internal/transport/context.go
new file mode 100644
index 000000000..3f22d4ec8
--- /dev/null
+++ b/internal/transport/context.go
@@ -0,0 +1,43 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package transport
+
+import "context"
+
+// ctxkey is our own unique context key type to prevent setting outside package.
+type ctxkey string
+
+// fastfailkey is our unique context key to indicate fast-fail is enabled.
+var fastfailkey = ctxkey("ff")
+
+// WithFastfail returns a Context which indicates that any http requests made
+// with it should return after the first failed attempt, instead of retrying.
+//
+// This can be used to fail quickly when you're making an outgoing http request
+// inside the context of an incoming http request, and you want to be able to
+// provide a snappy response to the user, instead of retrying + backing off.
+func WithFastfail(parent context.Context) context.Context {
+	return context.WithValue(parent, fastfailkey, struct{}{})
+}
+
+// IsFastfail returns true if the given context was created by WithFastfail.
+func IsFastfail(ctx context.Context) bool {
+	_, ok := ctx.Value(fastfailkey).(struct{})
+	return ok
+}