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Put a time-to-live on negative binary cache lookups

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Negative lookups are purged from the DB after a day, at most once per
day.  However, for non-"have" lookups (e.g. all except "nix-env
-qas"), negative lookups are ignored after one hour.  This is to
ensure that you don't have to wait a day for an operation like
"nix-env -i" to start using new binaries in the cache.

Should probably make this configurable.
This commit is contained in:
Eelco Dolstra 2012-09-13 16:39:16 -04:00
parent e03a8a1c92
commit 47ae3ce2ca
1 changed files with 30 additions and 3 deletions
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33
scripts/download-from-binary-cache.pl.in
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@ -19,10 +19,14 @@ my $gotCaches = 0;
my $maxParallelRequests = int($Nix::Config::config{"binary-caches-parallel-connections"} // 150);
$maxParallelRequests = 1 if $maxParallelRequests < 1;
my $ttlNegative = 24 * 3600; # when to purge negative lookups from the database
my $ttlNegativeUse = 3600; # how long negative lookups are valid for non-"have" lookups
my $didExpiration = 0;
my $debug = ($ENV{"NIX_DEBUG_SUBST"} // "") eq 1;
open(STDERR, ">>/dev/tty") if $debug;
my ($dbh, $queryCache, $insertNAR, $queryNAR, $insertNARExistence, $queryNARExistence);
my ($dbh, $queryCache, $insertNAR, $queryNAR, $insertNARExistence, $queryNARExistence, $expireNARExistence);
my $curlm = WWW::Curl::Multi->new;
my $activeRequests = 0;
@ -149,6 +153,8 @@ EOF
);
EOF
$dbh->do("create index if not exists NARExistenceByExistTimestamp on NARExistence (exist, timestamp)");
$queryCache = $dbh->prepare("select id, storeDir, wantMassQuery from BinaryCaches where url = ?") or die;
$insertNAR = $dbh->prepare(
@ -160,7 +166,9 @@ EOF
$insertNARExistence = $dbh->prepare(
"insert or replace into NARExistence(cache, storePath, exist, timestamp) values (?, ?, ?, ?)") or die;
$queryNARExistence = $dbh->prepare("select exist from NARExistence where cache = ? and storePath = ?") or die;
$queryNARExistence = $dbh->prepare("select exist, timestamp from NARExistence where cache = ? and storePath = ?") or die;
$expireNARExistence = $dbh->prepare("delete from NARExistence where exist = ? and timestamp < ?") or die;
}
@ -238,6 +246,8 @@ sub getAvailableCaches {
next if $storeDir ne $Nix::Config::storeDir;
push @caches, { id => $id, url => $url, wantMassQuery => $wantMassQuery };
}
expireNegative();
}
@ -324,7 +334,7 @@ sub negativeHit {
my ($storePath, $cache) = @_;
$queryNARExistence->execute($cache->{id}, basename($storePath));
my $res = $queryNARExistence->fetchrow_hashref();
return defined $res && $res->{exist} == 0;
return defined $res && $res->{exist} == 0 && time() - $res->{timestamp} < $ttlNegativeUse;
}
@ -337,6 +347,21 @@ sub positiveHit {
}
sub expireNegative {
return if $didExpiration;
$didExpiration = 1;
my $time = time();
# Round up to the next multiple of the TTL to ensure that we do
# expiration only once per time interval. E.g. if $ttlNegative ==
# 3600, we expire entries at most once per hour. This is
# presumably faster than expiring a few entries per request (and
# thus doing a transaction).
my $limit = (int($time / $ttlNegative) - 1) * $ttlNegative;
$expireNARExistence->execute($limit, 0);
print STDERR "expired ", $expireNARExistence->rows, " negative entries\n" if $debug;
}
sub printInfo {
my ($storePath, $info) = @_;
print "$storePath\n";
@ -512,11 +537,13 @@ if ($ARGV[0] eq "--query") {
my ($cmd, @args) = split " ", $_;
if ($cmd eq "have") {
print STDERR "checking binary caches for existence of @args\n" if $debug;
printSubstitutablePaths(@args);
print "\n";
}
elsif ($cmd eq "info") {
print STDERR "checking binary caches for info on @args\n" if $debug;
printInfoParallel(@args);
print "\n";
}