vfs: add remote control for directory cache flushing

docs/content/rc.md

@@ -9,6 +9,8 @@ date: "2018-03-05"
 If rclone is run with the `--rc` flag then it starts an http server
 which can be used to remote control rclone.
 
+**NB** this is experimental and everything here is subject to change!
+
 ## Supported parameters
 
 #### --rc ####
@@ -54,6 +56,58 @@ rc` command.
 
 You can use it like this
 
+```
+$ rclone rc rc/noop param1=one param2=two
+{
+	"param1": "one",
+	"param2": "two"
+}
+```
+
+Run `rclone rc` on its own to see the help for the installed remote
+control commands.
+
+## Supported commands
+
+### cache/expire: Purge a remote from cache
+
+Purge a remote from the cache backend. Supports either a directory or a file.
+Params:
+  - remote = path to remote (required)
+  - withData = true/false to delete cached data (chunks) as well (optional)
+
+### vfs/forget: Forget files or directories in the directory cache.
+
+This forgets the paths in the directory cache causing them to be
+re-read from the remote when needed.
+
+If no paths are passed in then it will forget all the paths in the
+directory cache.
+
+    rclone rc vfs/forget
+
+Otherwise pass files or dirs in as file=path or dir=path.  Any
+parameter key starting with file will forget that file and any
+starting with dir will forget that dir, eg
+
+    rclone rc vfs/forget file=hello file2=goodbye dir=home/junk
+
+### rc/noop: Echo the input to the output parameters
+
+This echoes the input parameters to the output parameters for testing
+purposes.  It can be used to check that rclone is still alive and to
+check that parameter passing is working properly.
+
+### rc/error: This returns an error
+
+This returns an error with the input as part of its error string.
+Useful for testing error handling.
+
+### rc/list: List all the registered remote control commands
+
+This lists all the registered remote control commands as a JSON map in
+the commands response.
+
 ## Accessing the remote control via HTTP
 
 Rclone implements a simple HTTP based protocol.

vfs/help.go

@@ -18,6 +18,15 @@ like this:
 
     kill -SIGHUP $(pidof rclone)
 
+If you configure rclone with a [remote control](/rc) then you can use
+rclone rc to flush the whole directory cache:
+
+    rclone rc vfs/forget
+
+Or individual files or directories:
+
+    rclone rc vfs/forget file=path/to/file dir=path/to/dir
+
 ### File Caching
 
 **NB** File caching is **EXPERIMENTAL** - use with care!

vfs/rc.go

@@ -0,0 +1,64 @@
+package vfs
+
+import (
+	"strings"
+
+	"github.com/ncw/rclone/fs"
+	"github.com/ncw/rclone/fs/rc"
+	"github.com/pkg/errors"
+)
+
+// Add remote control for the VFS
+func (vfs *VFS) addRC() {
+	rc.Add(rc.Call{
+		Path: "vfs/forget",
+		Fn: func(in rc.Params) (out rc.Params, err error) {
+			root, err := vfs.Root()
+			if err != nil {
+				return nil, err
+			}
+
+			forgotten := []string{}
+			if len(in) == 0 {
+				root.ForgetAll()
+			} else {
+				for k, v := range in {
+					path, ok := v.(string)
+					if !ok {
+						return out, errors.Errorf("value must be string %q=%v", k, v)
+					}
+					path = strings.Trim(path, "/")
+					if strings.HasPrefix(k, "file") {
+						root.ForgetPath(path, fs.EntryObject)
+					} else if strings.HasPrefix(k, "dir") {
+						root.ForgetPath(path, fs.EntryDirectory)
+					} else {
+						return out, errors.Errorf("unknown key %q", k)
+					}
+					forgotten = append(forgotten, path)
+				}
+			}
+			out = rc.Params{
+				"forgotten": forgotten,
+			}
+			return out, nil
+		},
+		Title: "Forget files or directories in the directory cache.",
+		Help: `
+This forgets the paths in the directory cache causing them to be
+re-read from the remote when needed.
+
+If no paths are passed in then it will forget all the paths in the
+directory cache.
+
+    rclone rc vfs/forget
+
+Otherwise pass files or dirs in as file=path or dir=path.  Any
+parameter key starting with file will forget that file and any
+starting with dir will forget that dir, eg
+
+    rclone rc vfs/forget file=hello file2=goodbye dir=home/junk
+
+`,
+	})
+}

vfs/vfs.go

@@ -233,6 +233,9 @@ func New(f fs.Fs, opt *Options) *VFS {
 		panic(fmt.Sprintf("failed to create local cache: %v", err))
 	}
 	vfs.cache = cache
+
+	// add the remote control
+	vfs.addRC()
 	return vfs
 }