1 /*
2 * Copyright (C) 2005-2015 Schlichtherle IT Services.
3 * All rights reserved. Use is subject to license terms.
4 */
5 package net.java.truevfs.kernel.spec;
6
7 import javax.annotation.CheckForNull;
8 import net.java.truecommons.shed.ImplementationsShouldExtend;
9
10 /**
11 * Defines common properties of any file system.
12 * <p>
13 * Implementations should be safe for multi-threaded access.
14 *
15 * @see FsController
16 * @see FsManager
17 * @author Christian Schlichtherle
18 */
19 @ImplementationsShouldExtend(FsAbstractModel.class)
20 public interface FsModel {
21
22 /**
23 * Returns the mount point of the file system.
24 * The mount point may be used to construct error messages or to locate
25 * and access file system meta data which is stored outside the file system,
26 * e.g. passwords for RAES encrypted ZIP files.
27 *
28 * @return The mount point of the file system.
29 */
30 FsMountPoint getMountPoint();
31
32 /**
33 * Returns the parent file system model or {@code null} if and only if the
34 * file system is not federated, i.e. if it's not a member of a parent file
35 * system.
36 *
37 * @return The nullable parent file system model.
38 */
39 @CheckForNull FsModel getParent();
40
41 /**
42 * Returns {@code true} if and only if some state associated with the
43 * federated file system has been modified so that the
44 * corresponding {@link FsController} must not get discarded until
45 * the next call to {@link FsController#sync sync}.
46 * <p>
47 * An implementation may always return {@code false} if the associated
48 * file system controller is stateless.
49 *
50 * @return {@code true} if and only if some state associated with the
51 * federated file system has been modified so that the
52 * corresponding {@link FsController} must not get discarded until
53 * the next {@link FsController#sync sync}.
54 */
55 boolean isMounted();
56
57 /**
58 * Sets the value of the property {@link #isMounted() mounted}.
59 * Only file system controllers should call this method in order to
60 * register themselves for a call their {@link FsController#sync} method.
61 * <p>
62 * An implementation may ignore calls to this method if the associated
63 * file system controller is stateless.
64 *
65 * @param mounted the new value of this property.
66 */
67 void setMounted(boolean mounted);
68
69 /**
70 * A factory for {@linkplain FsModel file system models}.
71 * <p>
72 * Implementations should be safe for multi-threaded access.
73 *
74 * @param <Context> The type of the calling context.
75 * @since TrueVFS 0.11
76 * @author Christian Schlichtherle
77 */
78 interface Factory<Context> {
79
80 /**
81 * Returns a new file system model for the given mount point.
82 * This is a pure function without side effects.
83 * <p>
84 * When called, you may assert the following precondition:
85 * <pre>{@code
86 * assert null == parent
87 * ? null == mountPoint.getParent()
88 * : parent.getMountPoint().equals(mountPoint.getParent());
89 * }</pre>
90 *
91 * @param context the calling context.
92 * @param mountPoint the mount point of the file system.
93 * @param parent the nullable parent file system model.
94 * @return A new file system model for the given mount point.
95 */
96 FsModel newModel(
97 Context context,
98 FsMountPoint mountPoint,
99 @CheckForNull FsModel parent);
100 }
101 }