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/**
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* Copyright © 2019, Oracle and/or its affiliates. All rights reserved.
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*
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* Licensed under the Universal Permissive License v 1.0 as shown at
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* http://oss.oracle.com/licenses/upl
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*
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*/
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#ifndef FWG_H
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#define FWG_H
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/* File work graph. */
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/* A file work graph is a directed acyclic graph (DAG) of nodes, each
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* containing an fwobject.
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* This structure is multithreaded, with some threads adding nodes,
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* and some removing nodes that have no predecessors.
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*
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* The graph has a budget, measured in bytes. The graph avoids
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* allocating more memory than the budget permits, so if you try to
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* add too many nodes, you will stall until some other thread removes
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* objects.
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* A fwobject is opaque from this module's perspective.
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*
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* fwobjects are identified by a pathname (a string). We assume that
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* symlinks aren't being used to confuse us by using different
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* pathnames for the same directory.
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*
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* To create an object (a file, hardlink, symlink, or directory, for
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* example), the directory of the object must have been created, and
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* the previous object in the same directory must have been created.
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* For hardlinks, the linked-to object must also have been created.
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*
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* To make this work we keep a hash table that maps from pathnames to nodes.
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*
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* Pathnames for regular files point at the node that creates the
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* file. When the file is created, we remove the hashtable entry.
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*
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* Pathnames for directories point at a node for the directory
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* creation. When the directory is created, we remove the hashtable
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* entry.
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*
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* Pathnames for directories also can point at the latest node that
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* has been added for a file that will be created in that directory.
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*/
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#include <stddef.h>
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struct fwg;
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struct fwgnode;
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struct fwobject;
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struct fwg *mk_fwg(size_t budget);
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// Effect: Make and return a fwg with a given budget.
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struct fwg *fwg_destroy(struct fwg *fwg);
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// Effect: Waits until everything has been removed and frees the
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// resources used by fwg. You may not add anything else after this
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// has been invoked.
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void fwg_add1(struct fwg *fwg,
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const char *name, struct fwobject *fwobject, size_t budget,
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const char *prev);
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// Usage: To create a file, name is the name of the file and prev is
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// the name of the directory containing the file.
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void fwg_add2(struct fwg *fwg,
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const char *name, struct fwobject *fwobject, size_t budget,
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const char *prev1, const char *prev2);
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void fwg_add3(struct fwg *fwg,
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const char *name, struct fwobject *fwobject, size_t budget,
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const char *prev1, const char *prev2, const char *prev3);
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void fwg_end_of_nodes(struct fwg *fwg);
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int fwg_get_ready_node(struct fwg *fwg,
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struct fwobject **fwobject,
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struct fwgnode **handle);
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void fwg_finish_node(struct fwg *fwg, struct fwgnode *handle);
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#endif
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