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Diffstat (limited to 'pkg/sentry/context/context.go')
| -rw-r--r-- | pkg/sentry/context/context.go | 141 |
1 files changed, 0 insertions, 141 deletions
diff --git a/pkg/sentry/context/context.go b/pkg/sentry/context/context.go deleted file mode 100644 index 23e009ef3..000000000 --- a/pkg/sentry/context/context.go +++ /dev/null @@ -1,141 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Package context defines an internal context type. -// -// The given Context conforms to the standard Go context, but mandates -// additional methods that are specific to the kernel internals. Note however, -// that the Context described by this package carries additional constraints -// regarding concurrent access and retaining beyond the scope of a call. -// -// See the Context type for complete details. -package context - -import ( - "context" - "time" - - "gvisor.dev/gvisor/pkg/amutex" - "gvisor.dev/gvisor/pkg/log" -) - -type contextID int - -// Globally accessible values from a context. These keys are defined in the -// context package to resolve dependency cycles by not requiring the caller to -// import packages usually required to get these information. -const ( - // CtxThreadGroupID is the current thread group ID when a context represents - // a task context. The value is represented as an int32. - CtxThreadGroupID contextID = iota -) - -// ThreadGroupIDFromContext returns the current thread group ID when ctx -// represents a task context. -func ThreadGroupIDFromContext(ctx Context) (tgid int32, ok bool) { - if tgid := ctx.Value(CtxThreadGroupID); tgid != nil { - return tgid.(int32), true - } - return 0, false -} - -// A Context represents a thread of execution (hereafter "goroutine" to reflect -// Go idiosyncrasy). It carries state associated with the goroutine across API -// boundaries. -// -// While Context exists for essentially the same reasons as Go's standard -// context.Context, the standard type represents the state of an operation -// rather than that of a goroutine. This is a critical distinction: -// -// - Unlike context.Context, which "may be passed to functions running in -// different goroutines", it is *not safe* to use the same Context in multiple -// concurrent goroutines. -// -// - It is *not safe* to retain a Context passed to a function beyond the scope -// of that function call. -// -// In both cases, values extracted from the Context should be used instead. -type Context interface { - log.Logger - amutex.Sleeper - context.Context - - // UninterruptibleSleepStart indicates the beginning of an uninterruptible - // sleep state (equivalent to Linux's TASK_UNINTERRUPTIBLE). If deactivate - // is true and the Context represents a Task, the Task's AddressSpace is - // deactivated. - UninterruptibleSleepStart(deactivate bool) - - // UninterruptibleSleepFinish indicates the end of an uninterruptible sleep - // state that was begun by a previous call to UninterruptibleSleepStart. If - // activate is true and the Context represents a Task, the Task's - // AddressSpace is activated. Normally activate is the same value as the - // deactivate parameter passed to UninterruptibleSleepStart. - UninterruptibleSleepFinish(activate bool) -} - -// NoopSleeper is a noop implementation of amutex.Sleeper and UninterruptibleSleep -// methods for anonymous embedding in other types that do not implement sleeps. -type NoopSleeper struct { - amutex.NoopSleeper -} - -// UninterruptibleSleepStart does nothing. -func (NoopSleeper) UninterruptibleSleepStart(bool) {} - -// UninterruptibleSleepFinish does nothing. -func (NoopSleeper) UninterruptibleSleepFinish(bool) {} - -// Deadline returns zero values, meaning no deadline. -func (NoopSleeper) Deadline() (time.Time, bool) { - return time.Time{}, false -} - -// Done returns nil. -func (NoopSleeper) Done() <-chan struct{} { - return nil -} - -// Err returns nil. -func (NoopSleeper) Err() error { - return nil -} - -// logContext implements basic logging. -type logContext struct { - log.Logger - NoopSleeper -} - -// Value implements Context.Value. -func (logContext) Value(key interface{}) interface{} { - return nil -} - -// bgContext is the context returned by context.Background. -var bgContext = &logContext{Logger: log.Log()} - -// Background returns an empty context using the default logger. -// -// Users should be wary of using a Background context. Please tag any use with -// FIXME(b/38173783) and a note to remove this use. -// -// Generally, one should use the Task as their context when available, or avoid -// having to use a context in places where a Task is unavailable. -// -// Using a Background context for tests is fine, as long as no values are -// needed from the context in the tested code paths. -func Background() Context { - return bgContext -} |