* Reverse mappings for the successor and substitute mappings.

This commit is contained in:
Eelco Dolstra 2003-10-10 14:46:28 +00:00
parent 1eb4da156c
commit d3d5e77810
6 changed files with 68 additions and 27 deletions

View file

@ -7,7 +7,9 @@ Database nixDB;
TableId dbValidPaths;
TableId dbSuccessors;
TableId dbSuccessorsRev;
TableId dbSubstitutes;
TableId dbSubstitutesRev;
string nixStore = "/UNINIT";
@ -24,7 +26,9 @@ void openDB()
nixDB.open(nixDBPath);
dbValidPaths = nixDB.openTable("validpaths");
dbSuccessors = nixDB.openTable("successors");
dbSuccessorsRev = nixDB.openTable("successors-rev");
dbSubstitutes = nixDB.openTable("substitutes");
dbSubstitutesRev = nixDB.openTable("substitutes-rev");
}

View file

@ -33,6 +33,13 @@ extern TableId dbValidPaths;
extern TableId dbSuccessors;
/* dbSuccessorsRev :: Path -> [Path]
The reverse mapping of dbSuccessors.
*/
extern TableId dbSuccessorsRev;
/* dbSubstitutes :: Path -> [Path]
Each pair $(p, [ps])$ tells Nix that it can realise any of the
@ -47,6 +54,13 @@ extern TableId dbSuccessors;
extern TableId dbSubstitutes;
/* dbSubstitutesRev :: Path -> [Path]
The reverse mapping of dbSubstitutes.
*/
extern TableId dbSubstitutesRev;
/* Path names. */
/* nixStore is the directory where we generally store atomic and

View file

@ -8,13 +8,6 @@
#include "globals.hh"
void registerSuccessor(const Transaction & txn,
const Path & path1, const Path & path2)
{
nixDB.setString(txn, dbSuccessors, path1, path2);
}
static Path useSuccessor(const Path & path)
{
string pathSucc;

View file

@ -34,9 +34,5 @@ PathSet nixExprRequisites(const Path & nePath,
output paths are completely contained in the set `outputs'. */
PathSet findGenerators(const PathSet & outputs);
/* Register a successor. */
void registerSuccessor(const Transaction & txn,
const Path & path1, const Path & path2);
#endif /* !__NORMALISE_H */

View file

@ -81,26 +81,50 @@ void copyPath(const Path & src, const Path & dst)
}
void registerSuccessor(const Transaction & txn,
const Path & path1, const Path & path2)
{
Path known;
if (nixDB.queryString(txn, dbSuccessors, path1, known) &&
known != path2)
{
throw Error(format(
"the `impossible' happened: expression in path "
"`%1%' appears to have multiple successors "
"(known `%2%', new `%3%'")
% path1 % known % path2);
}
Paths revs;
nixDB.queryStrings(txn, dbSuccessorsRev, path2, revs);
revs.push_back(path1);
nixDB.setString(txn, dbSuccessors, path1, path2);
nixDB.setStrings(txn, dbSuccessorsRev, path2, revs);
}
void registerSubstitute(const Path & srcPath, const Path & subPath)
{
#if 0
Strings subs;
queryListDB(nixDB, dbSubstitutes, srcId, subs); /* non-existence = ok */
for (Strings::iterator it = subs.begin(); it != subs.end(); it++)
if (parseHash(*it) == subId) return;
subs.push_back(subId);
setListDB(nixDB, dbSubstitutes, srcId, subs);
#endif
/* For now, accept only one substitute per id. */
Strings subs;
subs.push_back(subPath);
Transaction txn(nixDB);
Paths subs;
nixDB.queryStrings(txn, dbSubstitutes, srcPath, subs);
if (find(subs.begin(), subs.end(), subPath) != subs.end()) {
/* Nothing to do if the substitute is already known. */
txn.abort();
return;
}
subs.push_front(subPath); /* new substitutes take precedence */
Paths revs;
nixDB.queryStrings(txn, dbSubstitutesRev, subPath, revs);
revs.push_back(srcPath);
nixDB.setStrings(txn, dbSubstitutes, srcPath, subs);
nixDB.setStrings(txn, dbSubstitutesRev, subPath, revs);
txn.commit();
}

View file

@ -12,6 +12,16 @@ using namespace std;
/* Copy a path recursively. */
void copyPath(const Path & src, const Path & dst);
/* Register a successor. This function accepts a transaction handle
so that it can be enclosed in an atomic operation with calls to
registerValidPath(). This must be atomic, since if we register a
successor for a derivation without registering the paths built in
the derivation, we have a successor with dangling pointers, and if
we do it in reverse order, we can get an obstructed build (since to
rebuild the successor, the outputs paths must not exist). */
void registerSuccessor(const Transaction & txn,
const Path & path1, const Path & path2);
/* Register a substitute. */
void registerSubstitute(const Path & srcPath, const Path & subPath);