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#ifndef __GLOBALS_H
#define __GLOBALS_H
#include <string>
#include "db.hh"
using namespace std;
extern Database nixDB;
/* Database tables. */
/* dbPath2Id :: Path -> FSId
Each pair (p, id) records that path $p$ contains an expansion of
$id$. */
extern TableId dbPath2Id;
/* dbId2Paths :: FSId -> [Path]
A mapping from ids to lists of paths. */
extern TableId dbId2Paths;
/* dbSuccessors :: FSId -> FSId
Each pair $(id_1, id_2)$ in this mapping records the fact that a
successor of an fstate expression stored in a file with identifier
$id_1$ is stored in a file with identifier $id_2$.
Note that a term $y$ is successor of $x$ iff there exists a
sequence of rewrite steps that rewrites $x$ into $y$.
*/
extern TableId dbSuccessors;
/* dbSubstitutes :: FSId -> [FSId]
Each pair $(id, [ids])$ tells Nix that it can realise any of the
fstate expressions referenced by the identifiers in $ids$ to
generate a path with identifier $id$.
The main purpose of this is for distributed caching of derivates.
One system can compute a derivate with hash $h$ and put it on a
website (as a Nix archive), for instance, and then another system
can register a substitute for that derivate. The substitute in
this case might be an fstate expression that fetches the Nix
archive.
*/
extern TableId dbSubstitutes;
/* Path names. */
/* nixStore is the directory where we generally store atomic and
derived files. */
extern string nixStore;
extern string nixDataDir; /* !!! fix */
/* nixLogDir is the directory where we log various operations. */
extern string nixLogDir;
/* nixDBPath is the path name of our Berkeley DB environment. */
extern string nixDBPath;
/* Open the database environment. */
void openDB();
/* Create the required database tables. */
void initDB();
#endif /* !__GLOBALS_H */
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