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* nix-prefetch-url: support caching. If the environment variable

Browse source 
NIX_DOWNLOAD_CACHE is set, then nix-prefetch-url will store the hash
  and timestamp of downloaded files in the directory
  $NIX_DOWNLOAD_CACHE.  This allows it to figure out if the file is
  still in the Nix store.
This commit is contained in:
Eelco Dolstra 2007-08-09 23:16:44 +00:00
parent ef240bc0d5
commit f881f7a017
3 changed files with 58 additions and 13 deletions
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3
scripts/nix-channel.in
View file

@ -98,7 +98,8 @@ sub update {
my $fullURL = "$url/nixexprs.tar.bz2";
print "downloading Nix expressions from `$fullURL'...\n";
$ENV{"PRINT_PATH"} = 1;
my ($hash, $path) = `@bindir@/nix-prefetch-url '$fullURL' 2> /dev/null`;
$ENV{"QUIET"} = 1;
my ($hash, $path) = `@bindir@/nix-prefetch-url '$fullURL'`;
die "cannot fetch `$fullURL'" if $? != 0;
chomp $path;
$inputs .= '"' . $channelName . '"' . " " . $path . " ";

66
scripts/nix-prefetch-url.in
View file

@ -36,6 +36,12 @@ if test -n "$expHash"; then
fi
doDownload() {
@curl@ $cacheFlags --fail -# --show-error --location --max-redirs 20 --disable-epsv \
--cookie-jar $tmpPath/cookies "$url" -o $tmpFile
}
# If we don't know the hash or a file with that hash doesn't exist,
# download the file and add it to the store.
if test -z "$finalPath"; then
@ -44,22 +50,60 @@ if test -z "$finalPath"; then
tmpFile=$tmpPath/$name
mkdir $tmpPath
# Optionally do timestamp-based caching of the download.
# Actually, the only thing that we cache in $NIX_DOWNLOAD_CACHE is
# the hash and the timestamp of the file at $url. The caching of
# the file *contents* is done in Nix store, where it can be
# garbage-collected independently.
if test -n "$NIX_DOWNLOAD_CACHE"; then
urlHash="$(echo -n "$url" | nix-hash --type sha256 --base32 --flat /dev/stdin)"
echo "$url" > "$NIX_DOWNLOAD_CACHE/$urlHash.url"
cachedHashFN="$NIX_DOWNLOAD_CACHE/$urlHash.$hashType"
cachedTimestampFN="$NIX_DOWNLOAD_CACHE/$urlHash.stamp"
cacheFlags="--remote-time"
if test -e "$cachedTimestampFN" -a -e "$cachedHashFN"; then
# Only download the file if it is newer than the cached version.
cacheFlags="$cacheFlags --time-cond $cachedTimestampFN"
fi
fi
# Perform the download.
@curl@ --fail --location --max-redirs 20 --disable-epsv \
--cookie-jar $tmpPath/cookies "$url" > $tmpFile
doDownload
# Compute the hash.
hash=$(@bindir@/nix-hash --type "$hashType" $hashFormat --flat $tmpFile)
if ! test -n "$QUIET"; then echo "hash is $hash" >&2; fi
if test -n "$NIX_DOWNLOAD_CACHE" -a ! -e $tmpFile; then
# Curl didn't create $tmpFile, so apparently there's no newer
# file on the server.
hash=$(cat $cachedHashFN)
finalPath=$(@bindir@/nix-store --print-fixed-path "$hashType" "$hash" "$name")
if ! @bindir@/nix-store --check-validity "$finalPath" 2> /dev/null; then
echo "cached contents of \`$url' disappeared, redownloading..." >&2
finalPath=
cacheFlags="--remote-time"
doDownload
fi
fi
# Add the downloaded file to the Nix store.
finalPath=$(@bindir@/nix-store --add-fixed "$hashType" $tmpFile)
if test -z "$finalPath"; then
if test -n "$tmpPath"; then rm -rf $tmpPath || true; fi
# Compute the hash.
hash=$(@bindir@/nix-hash --type "$hashType" $hashFormat --flat $tmpFile)
if ! test -n "$QUIET"; then echo "hash is $hash" >&2; fi
if test -n "$expHash" -a "$expHash" != "$hash"; then
echo "hash mismatch for URL \`$url'" >&2
exit 1
if test -n "$NIX_DOWNLOAD_CACHE"; then
echo $hash > $cachedHashFN
touch -r $tmpFile $cachedTimestampFN
fi
# Add the downloaded file to the Nix store.
finalPath=$(@bindir@/nix-store --add-fixed "$hashType" $tmpFile)
if test -n "$tmpPath"; then rm -rf $tmpPath || true; fi
if test -n "$expHash" -a "$expHash" != "$hash"; then
echo "hash mismatch for URL \`$url'" >&2
exit 1
fi
fi
fi

2
scripts/nix-pull.in
View file

@ -39,7 +39,7 @@ sub processURL {
$url =~ s/\/$//;
print "obtaining list of Nix archives at $url...\n";
system("@curl@ --fail --silent --show-error --location --max-redirs 20 " .
system("@curl@ --fail -# --show-error --location --max-redirs 20 " .
"'$url' > '$manifest'") == 0
or die "curl failed: $?";