Commit graph

195 commits

Author SHA1 Message Date
Eelco Dolstra
ccc52adfb2 Add function queryPathFromHashPart()
To implement binary caches efficiently, Hydra needs to be able to map
the hash part of a store path (e.g. "gbg...zr7") to the full store
path (e.g. "/nix/store/gbg...kzr7-subversion-1.7.5").  (The binary
cache mechanism uses hash parts as a key for looking up store paths to
ensure privacy.)  However, doing a search in the Nix store for
/nix/store/<hash>* is expensive since it requires reading the entire
directory.  queryPathFromHashPart() prevents this by doing a cheap
database lookup.
2012-07-17 18:55:39 -04:00
Eelco Dolstra
09a6321aeb Replace hasSubstitutes() with querySubstitutablePaths()
querySubstitutablePaths() takes a set of paths, so this greatly
reduces daemon <-> client latency.
2012-07-11 17:52:18 -04:00
Eelco Dolstra
58ef4d9a95 Add a function queryValidPaths()
queryValidPaths() combines multiple calls to isValidPath() in one.
This matters when using the Nix daemon because it reduces latency.
For instance, on "nix-env -qas \*" it reduces execution time from 5.7s
to 4.7s (which is indistinguishable from the non-daemon case).
2012-07-11 11:08:47 -04:00
Eelco Dolstra
667d5f1936 Rename queryValidPaths() to queryAllValidPaths() 2012-07-11 10:49:04 -04:00
Eelco Dolstra
eb3036da87 Implement querySubstitutablePathInfos() in the daemon
Also removed querySubstitutablePathInfo().
2012-07-11 10:43:24 -04:00
Eelco Dolstra
11800e6198 download-from-binary-cache: parallelise fetching of NAR info files
Getting substitute information using the binary cache substituter has
non-trivial latency overhead.  A package or NixOS system configuration
can have hundreds of dependencies, and in the worst case (when the
local info cache is empty) we have to do a separate HTTP request for
each of these.  If the ping time to the server is t, getting N info
files will take tN seconds; e.g., with a ping time of 0.1s to
nixos.org, sequentially downloading 1000 info files (a typical NixOS
config) will take at least 100 seconds.

To fix this problem, the binary cache substituter can now perform
requests in parallel.  This required changing the substituter
interface to support a function querySubstitutablePathInfos() that
queries multiple paths at the same time, and rewriting queryMissing()
to take advantage of parallelism.  (Due to local caching,
parallelising queryMissing() is sufficient for most use cases, since
it's almost always called before building a derivation and thus fills
the local info cache.)

For example, parallelism speeds up querying all 1056 paths in a
particular NixOS system configuration from 116s to 2.6s.  It works so
well because the eccentricity of the top-level derivation in the
dependency graph is only 9.  So we only need 10 round-trips (when
using an unlimited number of parallel connections) to get everything.

Currently we do a maximum of 150 parallel connections to the server.
Thus it's important that the binary cache server (e.g. nixos.org) has
a high connection limit.  Alternatively we could use HTTP pipelining,
but WWW::Curl doesn't support it and libcurl has a hard-coded limit of
5 requests per pipeline.
2012-07-06 19:08:20 -04:00
Eelco Dolstra
4bc4da331a Reserve some disk space for the garbage collector
We can't open a SQLite database if the disk is full.  Since this
prevents the garbage collector from running when it's most needed, we
reserve some dummy space that we can free just before doing a garbage
collection.  This actually revives some old code from the Berkeley DB
days.

Fixes #27.
2012-05-29 22:59:12 -04:00
Eelco Dolstra
6387830c3b Merge pull request #2 from viric/master
Again, adding the sync option
2012-04-23 03:29:03 -07:00
Eelco Dolstra
117670be57 Make the garbage collector more concurrent
Make the garbage collector more concurrent by deleting valid paths
outside the region where we're holding the global GC lock.  This
should greatly reduce the time during which new builds are blocked,
since the deletion accounts for the vast majority of the time spent in
the GC.

To ensure that this is safe, the valid paths are invalidated and
renamed to some arbitrary path while we're holding the lock.  This
ensures that we when we finally delete the path, it's not a (newly)
valid or locked path.
2012-03-26 20:43:33 +02:00
Lluís Batlle i Rossell
85799bf89e Fixing the default of sync-before-registering
Setting 'false' as default, as suggested by Eelco.

I also added a comment about the setting in the code.
2012-03-22 20:05:54 +01:00
Lluís Batlle i Rossell
25de80e2b6 Adding a nix option to sync before registering a path, for non-ext*
filesystems.
2012-03-22 19:57:42 +01:00
Eelco Dolstra
19d9762ad5 nix-store --clear-failed-paths: Clear derivation outputs
If the argument to ‘nix-store --clear-failed-paths’ is a derivation,
then clear the failed state of its outputs.
2012-03-20 18:23:26 +01:00
Eelco Dolstra
2b4964f319 Restore progress indication during nix-copy-closure 2012-03-05 18:13:44 +01:00
Eelco Dolstra
8afd28a922 Remove dependency on sqlite3_table_column_metadata
Not all SQLite builds have the function sqlite3_table_column_metadata.
We were only using it in a schema upgrade check for compatibility with
databases that were probably never seen in the wild.  So remove it.
2012-03-01 16:06:49 +01:00
Eelco Dolstra
bd013b6f98 On Linux, make the Nix store really read-only by using the immutable bit
I was bitten one time too many by Python modifying the Nix store by
creating *.pyc files when run as root.  On Linux, we can prevent this
by setting the immutable bit on files and directories (as in ‘chattr
+i’).  This isn't supported by all filesystems, so it's not an error
if setting the bit fails.  The immutable bit is cleared by the garbage
collector before deleting a path.  The only tricky aspect is in
optimiseStore(), since it's forbidden to create hard links to an
immutable file.  Thus optimiseStore() temporarily clears the immutable
bit before creating the link.
2012-02-15 01:31:56 +01:00
Eelco Dolstra
5e57047d87 Fix a broken guard around utime()
Because of an outdated check for a timestamp of 0, we were calling
utime() even when it wasn't necessary.
2012-02-15 01:00:30 +01:00
Eelco Dolstra
b1004f40f7 * Reject a build if there is a cycle among the outputs. This is
necessary because existing code assumes that the references graph is
  acyclic.
2011-12-30 14:47:14 +00:00
Eelco Dolstra
194d21f9f6 * Sync with the trunk. 2011-12-16 23:33:01 +00:00
Eelco Dolstra
273b288a7e * importPath() -> importPaths(). Because of buffering of the input
stream it's now necessary for the daemon to process the entire
  sequence of exported paths, rather than letting the client do it.
2011-12-16 22:31:25 +00:00
Eelco Dolstra
e0bd307802 * Make the import operation through the daemon much more efficient
(way fewer roundtrips) by allowing the client to send data in bigger
  chunks.
* Some refactoring.
2011-12-16 19:44:13 +00:00
Eelco Dolstra
5a1b9ed0aa * Refactoring: move sink/source buffering into separate classes.
* Buffer the HashSink.  This speeds up hashing a bit because it
  prevents lots of calls to the hash update functions (e.g. nix-hash
  went from 9.3s to 8.7s of user time on the closure of my
  /var/run/current-system).
2011-12-15 16:19:53 +00:00
Eelco Dolstra
c8c0380744 * Remove unnecessary quotes. showPaths() already adds quotes. 2011-12-05 21:04:20 +00:00
Eelco Dolstra
000160f5b9 * In ‘nix-store --verify --check-contents’, repair missing hashes
rather than complain about them.
2011-12-02 17:52:18 +00:00
Eelco Dolstra
5bbd693cae * Add an API function exportPaths() that provides the functionality of
‘nix-store --export’.
* Add a Perl module that provides the functionality of
  ‘nix-copy-closure --to’.  This is used by build-remote.pl so it no
  longer needs to start a separate nix-copy-closure process.  Also, it
  uses the Perl API to do the export, so it doesn't need to start a
  separate nix-store process either.  As a result, nix-copy-closure
  and build-remote.pl should no longer fail on very large closures due
  to an "Argument list too long" error.  (Note that having very many
  dependencies in a single derivation can still fail because the
  environment can become too large.  Can't be helped though.)
2011-11-23 15:13:37 +00:00
Eelco Dolstra
c0b706213d * Boldly make SQLite WAL mode the default again. Hopefully the
intermittent problems are gone by now.  WAL mode is preferrable
  because it does way fewer fsyncs.
2011-11-07 21:11:59 +00:00
Shea Levy
af2e53fd48 Include all outputs of derivations in the closure of explicitly-passed derivation paths
This required adding a queryOutputDerivationNames function in the store API
2011-11-06 06:28:20 +00:00
Eelco Dolstra
13114daa3e * Ouch. A store upgrade could cause a substituter to be triggered,
causing a deadlock.
2011-09-12 09:07:43 +00:00
Eelco Dolstra
93227ff65c * Eliminate all uses of the global variable ‘store’ from libstore.
This should also fix:

    nix-instantiate: ./../boost/shared_ptr.hpp:254: T* boost::shared_ptr<T>::operator->() const [with T = nix::StoreAPI]: Assertion `px != 0' failed.

  which was caused by hashDerivationModulo() calling the ‘store’
  object (during store upgrades) before openStore() assigned it.
2011-08-31 21:11:50 +00:00
Eelco Dolstra
b2027f70d9 * Fix a huuuuge security hole in the Nix daemon. It didn't check that
derivations added to the store by clients have "correct" output
  paths (meaning that the output paths are computed by hashing the
  derivation according to a certain algorithm).  This means that a
  malicious user could craft a special .drv file to build *any*
  desired path in the store with any desired contents (so long as the
  path doesn't already exist).  Then the attacker just needs to wait
  for a victim to come along and install the compromised path.

  For instance, if Alice (the attacker) knows that the latest Firefox
  derivation in Nixpkgs produces the path

    /nix/store/1a5nyfd4ajxbyy97r1fslhgrv70gj8a7-firefox-5.0.1

  then (provided this path doesn't already exist) she can craft a .drv
  file that creates that path (i.e., has it as one of its outputs),
  add it to the store using "nix-store --add", and build it with
  "nix-store -r".  So the fake .drv could write a Trojan to the
  Firefox path.  Then, if user Bob (the victim) comes along and does

    $ nix-env -i firefox
    $ firefox

  he executes the Trojan injected by Alice.

  The fix is to have the Nix daemon verify that derivation outputs are
  correct (in addValidPath()).  This required some refactoring to move
  the hash computation code to libstore.
2011-07-20 18:10:47 +00:00
Eelco Dolstra
c931a7aec5 * Do a short sleep after SQLITE_BUSY. 2010-12-17 17:23:15 +00:00
Eelco Dolstra
3dd02580e3 * I forgot to catch SQLiteBusy in registerValidPaths(). So
registerValidPaths() now handles busy errors and registerValidPath()
  is simply a wrapper around it.
2010-12-14 13:25:20 +00:00
Eelco Dolstra
5833243c92 * Create /nix/var/nix/db if it's missing. 2010-12-13 13:42:34 +00:00
Eelco Dolstra
e4720b1a79 * Ignore the result of sqlite3_reset(). 2010-12-08 18:19:15 +00:00
Eelco Dolstra
8062d3af30 * `nix-store --verify --check-contents': don't hold the global GC lock
while checking the contents, since this operation can take a very
  long time to finish.  Also, fill in missing narSize fields in the DB
  while doing this.
2010-12-06 15:29:38 +00:00
Eelco Dolstra
de79d23f76 * Retry a transaction if SQLite returns SQLITE_BUSY. This can happen
even with a very long busy timeout, because SQLITE_BUSY is also
  returned to resolve deadlocks.  This should get rid of random
  "database is locked" errors.  This is kind of hard to test though.
* Fix a horrible bug in deleteFromStore(): deletePathWrapped() should
  be called after committing the transaction, not before, because the
  commit might not succeed.
2010-12-05 18:23:19 +00:00
Eelco Dolstra
bdf089f463 * Before a build, show the disk space that the downloaded store paths
will approximately require.
2010-11-17 14:31:42 +00:00
Eelco Dolstra
e60c962fb8 * Add an operation `nix-store -q --size'. 2010-11-17 12:40:52 +00:00
Eelco Dolstra
a3883cbd28 * Store the size of a store path in the database (to be precise, the
size of the NAR serialisation of the path, i.e., `nix-store --dump
  PATH').  This is useful for Hydra.
2010-11-16 17:11:46 +00:00
Eelco Dolstra
64fd29855a * Wrap deleteFromStore() in a transaction. Otherwise there might be a
race with other processes that add new referrers to a path,
  resulting in the garbage collector crashing with "foreign key
  constraint failed".  (Nix/4)
* Make --gc --print-dead etc. interruptible.
2010-10-14 15:55:51 +00:00
Eelco Dolstra
e4907411c2 * Only do "pragma journal_mode = ..." if the current journal mode
differs from the desired mode.  There is an open SQLite ticket
  `Executing "PRAGMA journal_mode" may delete journal file while it is
  in use.'
2010-09-01 11:36:22 +00:00
Eelco Dolstra
e2e168f7c2 `nix-store --verify' improvements:
* If a path has disappeared, check its referrers first, and don't try
  to invalidate paths that have valid referrers.  Otherwise we get a
  foreign key constraint violation.
* Read the whole Nix store directory instead of statting each valid
  path, which is slower.
* Acquire the global GC lock.
2010-08-31 11:47:31 +00:00
Eelco Dolstra
034f608e00 * Don't complain if the stored hash of a path is zero (unknown). 2010-08-24 14:25:33 +00:00
Eelco Dolstra
fd9c77dfc7 * Use SQLite 3.7.0's write-ahead logging (WAL mode). This is a lot
faster than the old mode when fsyncs are enabled, because it only
  performs an fsync() when doing a checkpoint, rather than at every
  commit.  Some timings for doing a "nix-instantiate /etc/nixos/nixos
  -A system" after modifying the stdenv setup script:

    42.5s - SQLite 3.6.23 with truncate mode and fsync
     3.4s - SQLite 3.6.23 with truncate mode and no fsync
    32.1s - SQLite 3.7.0 with truncate mode and fsync
    16.8s - SQLite 3.7.0 with WAL mode and fsync, auto-checkpoint
            every 1000 pages
     8.3s - SQLite 3.7.0 with WAL mode and fsync, auto-checkpoint
            every 8192 pages
     1.7s - SQLite 3.7.0 with WAL mode and no fsync

  The default is now to use WAL mode with fsyncs.  Because WAL doesn't
  work on remote filesystems such as NFS (as it uses shared memory),
  truncate mode can be re-enabled by setting the "use-sqlite-wal"
  option to false.
2010-08-04 17:35:59 +00:00
Eelco Dolstra
3e5e0faf9c * Okay, putting a lock on the temporary directory used by importPath()
doesn't work because the garbage collector doesn't actually look at
  locks.  So r22253 was stupid.  Use addTempRoot() instead.  Also,
  locking the temporary directory in exportPath() was silly because it
  isn't even in the store.
2010-06-21 11:08:09 +00:00
Eelco Dolstra
bf87cc44b4 * Sync with the trunk. 2010-06-21 07:55:38 +00:00
Eelco Dolstra
b57189174f * In importPath() and exportPath(), lock the temporary directory to
prevent it from being deleted by the garbage collector.
2010-06-14 08:34:48 +00:00
Eelco Dolstra
d1f6c0cbe3 * Replacing ValidPath rows doesn't work because it causes a constraint
violation of the Refs table.  So don't do that.
2010-06-08 13:38:28 +00:00
Eelco Dolstra
aa45027818 * Sync with the trunk. 2010-05-12 22:13:09 +00:00
Eelco Dolstra
6199f9b93e * Added a command `nix-store --clear-failed-paths <PATHS>' to clear
the "failed" status of the given store paths.  The special value `*'
  clears all failed paths.
2010-04-26 12:56:42 +00:00
Eelco Dolstra
2398af13c5 * Add an command `nix-store --query-failed-paths' to list the cached
failed paths (when using the `build-cache-failure' option).
2010-04-26 12:43:42 +00:00
Eelco Dolstra
efc7a579e8 * Don't use the ATerm library for parsing/printing .drv files. 2010-04-19 13:46:58 +00:00
Eelco Dolstra
1a65142ec4 * Remove a debug statement. 2010-03-10 12:46:25 +00:00
Eelco Dolstra
4c356acd04 * In `nix-store --export', abort if the contents of a path has
changed.  This prevents corrupt paths from spreading to other
  machines.  Note that checking the hash is cheap because we're
  hashing anyway (because of the --sign feature).
2010-03-09 14:32:03 +00:00
Eelco Dolstra
2e4ef03aa3 * Increase the sqlite timeout. 2010-03-08 10:35:45 +00:00
Eelco Dolstra
3f9e647ae8 * checkInterrupt() shouldn't be called from a destructor. 2010-03-02 19:04:17 +00:00
Eelco Dolstra
af565c348a * Support read-only access to the database. 2010-02-24 16:44:43 +00:00
Eelco Dolstra
e33f67ff0b * Refactor the upgrade / database initialisation logic a bit. 2010-02-24 16:30:20 +00:00
Eelco Dolstra
84a4dd5ff0 * Don't use fdatasync since it doesn't work on Snow Leopard.
* Don't refer to config.h in util.hh, because config.h is not
  installed (http://hydra.nixos.org/build/303053).
2010-02-24 15:46:06 +00:00
Eelco Dolstra
cfe742cfc5 * A function to query just the database id of a valid path. 2010-02-24 15:07:23 +00:00
Eelco Dolstra
9fd85c94de * Use `truncate' journal mode, which should be a bit faster. 2010-02-24 14:22:34 +00:00
Eelco Dolstra
a3c63d0d6c * Disable fsync() in SQLite if the fsync-metadata option is set to
false.
* Change the default for `fsync-metadata' to true.
* Disable `fsync-metadata' in `make check'.
2010-02-24 13:12:57 +00:00
Eelco Dolstra
90b6352d0a * Do registerValidPaths() in one transaction, which is much faster.
E.g. it cuts the runtime of the referrers test from 50s to 23s.
2010-02-24 12:48:00 +00:00
Eelco Dolstra
462bd50aef * Use normal (rather than full) synchronous mode, which I gather from
the description at http://www.sqlite.org/atomiccommit.html should be
  safe enough.
2010-02-24 10:57:57 +00:00
Eelco Dolstra
2b20318b0e 2010-02-22 14:24:37 +00:00
Eelco Dolstra
9cda616949 * The database needs a trigger to get rid of self-references to
prevent a foreign key constraint violation on the Refs table when
  deleting a path.
2010-02-22 14:18:55 +00:00
Eelco Dolstra
c4d388add4 * Get derivation outputs from the database instead of the .drv file,
which requires more I/O.
2010-02-22 12:44:36 +00:00
Eelco Dolstra
103cfee056 * Revert r19650 (implement gc-keep-outputs by looking for derivations
with the same name as the output) and instead use the
  DerivationOutputs table in the database, which is the correct way to
  to do things.
2010-02-22 11:44:17 +00:00
Eelco Dolstra
299ff64812 * Put the derivation outputs in the database. This is useful for the
garbage collector.
2010-02-22 11:15:50 +00:00
Eelco Dolstra
1930570ad9 * Foreign key support in SQLite is not a persistent setting, so enable
it at startup.
* Implement negative caching.  Now `make check' passes.
2010-02-19 17:15:22 +00:00
Eelco Dolstra
9c9a88e9e2 * Implement more stuff. 2010-02-19 16:43:25 +00:00
Eelco Dolstra
762cee72cc * Implement registerValidPath(). 2010-02-19 16:04:51 +00:00
Eelco Dolstra
268f9aaf28 * Implemented queryValidPaths() and verifyStore(). 2010-02-18 16:51:27 +00:00
Eelco Dolstra
836e5b6f57 * Implemented queryReferrers(). 2010-02-18 16:21:59 +00:00
Eelco Dolstra
77cb9e3fb1 * Implement queryPathInfo(). 2010-02-18 15:52:57 +00:00
Eelco Dolstra
885e22b16e * Implement isValidPath(). 2010-02-18 15:11:08 +00:00
Eelco Dolstra
cfb09e0fad * Automatically abort transactions if they go out of scope without
committing.
2010-02-18 14:40:07 +00:00
Eelco Dolstra
e0305bb7a8 * Some wrapper objects to ensure that SQLite objects are properly
destroyed.
2010-02-18 14:30:42 +00:00
Eelco Dolstra
a053d2d8e5 * Add the deriver to the ValidPaths table. In principle we could now
store all the derivers of a path efficiently.  But that opens a big
  can of worms with respect to garbage collector semantics.
2010-02-18 13:48:18 +00:00
Eelco Dolstra
dbddac0fe9 * Assign an integer id to every row in the ValidPaths table in order
to make the Refs table more space-efficient.  For instance, this
  reduces the size of the database on my laptop from 93 MiB to 18
  MiB.  (It was 72 MiB with the old schema on an ext3 disk with a 1
  KiB block size.)
2010-02-18 13:40:46 +00:00
Eelco Dolstra
c1a07f9445 * Convert the Nix database to SQLite. 2010-02-18 13:16:59 +00:00
Eelco Dolstra
07ffdc2862 * Added an option "fsync-metadata" to fsync() changes to
/nix/var/nix/db.
* Removed the function writeStringToFile since it does (almost) the
  same thing as writeFile.
2010-01-29 12:22:58 +00:00
Eelco Dolstra
ad529fb89f * Don't consider a store path valid if its info file exists but is
zero bytes long.  That makes Nix more robust in case of crashes
  (especially on ext4).
2010-01-29 11:53:58 +00:00
Eelco Dolstra
327a232c85 * Remove support for old (before Nix 0.12pre12020) databases. 2009-11-06 01:15:44 +00:00
Eelco Dolstra
c7057fc1f2 * And some more. 2009-09-24 07:39:55 +00:00
Eelco Dolstra
676e07902e * Darwin hack. 2009-09-23 18:04:55 +00:00
Eelco Dolstra
64e89980e8 * Create some state directories automatically as a convenience. 2009-09-23 17:05:51 +00:00
Eelco Dolstra
14bc3ce3d6 * Canonicalise timestamps in the Nix store to 1 (1970-01-01 00:00:01
UTC) rather than 0 (00:00:00).  1 is a better choice because some
  programs use 0 as a special value.  For instance, the Template
  Toolkit uses a timestamp of 0 to denote the non-existence of a file,
  so it barfs on files in the Nix store (see
  template-toolkit-nix-store.patch in Nixpkgs).  Similarly, Maya 2008
  fails to load script directories with a timestamp of 0 and can't be
  patched because it's closed source.

  This will also shut up those "implausibly old time stamp" GNU tar
  warnings.
2009-06-13 16:30:58 +00:00
Eelco Dolstra
d5eab2fc82 * Use foreach in a lot of places. 2009-04-21 11:52:16 +00:00
Eelco Dolstra
8f1bf28505 * nix-store --verify: don't bail out if a referenced path is missing.
(It can't fix it though.)
2009-04-21 11:06:27 +00:00
Eelco Dolstra
4e646b0ddb * Fix a few "comparison is always false/true due to limited range of
data type" warnings on 64-bit platforms.  The one in parser.y is
  likely to be a real bug.
2009-04-16 12:03:17 +00:00
Eelco Dolstra
c7152c8f97 * Don't use the non-standard __gnu_cxx::stdio_filebuf class. 2009-03-28 19:41:53 +00:00
Eelco Dolstra
cb85bc396e * Create /nix/store if it doesn't exist. 2009-03-27 14:19:04 +00:00
Eelco Dolstra
92f525ecf4 * Negative caching, i.e. caching of build failures. Disabled by
default.  This is mostly useful for Hydra.
2009-03-25 21:05:42 +00:00
Eelco Dolstra
77d272623f * NAR archives: handle files larger than 2^32 bytes. Previously it
would just silently store only (fileSize % 2^32) bytes.
* Use posix_fallocate if available when unpacking archives.
* Provide a better error message when trying to unpack something that
  isn't a NAR archive.
2009-03-22 17:36:43 +00:00
Eelco Dolstra
b682fae9d9 * Build hooks: use nix-store --import. This prevents a redundant
scan for runtime dependencies (i.e. the local machine shouldn't do a
  scan that the remote machine has already done).  Also pipe directly
  into `nix-store --import': don't use a temporary file.
2009-02-02 17:24:10 +00:00
Eelco Dolstra
8fce03e0ad * nix-store --verify: repair bad hash fields in the metadata file. 2008-12-16 13:28:18 +00:00
Eelco Dolstra
82ae85de27 * addToStore() in nix-worker: don't write the NAR dump received from
the client to a temporary directory, as that is highly inefficient.
2008-12-03 18:05:14 +00:00
Eelco Dolstra
ff762fb499 * Pass HashType values instead of strings. 2008-12-03 16:10:17 +00:00
Eelco Dolstra
1307b22223 * Made addToStore() a lot more efficient: it no longer reads the path
being copied 3 times in the worst case.  It doesn't run in constant space,
  but it didn't do that anyway.
2008-12-03 15:51:17 +00:00
Eelco Dolstra
64519cfd65 * Unify the treatment of sources copied to the store, and recursive
SHA-256 outputs of fixed-output derivations.  I.e. they now produce
  the same store path:

  $ nix-store --add x
  /nix/store/j2fq9qxvvxgqymvpszhs773ncci45xsj-x

  $ nix-store --add-fixed --recursive sha256 x
  /nix/store/j2fq9qxvvxgqymvpszhs773ncci45xsj-x

  the latter being the same as the path that a derivation

    derivation {
      name = "x";
      outputHashAlgo = "sha256";
      outputHashMode = "recursive";
      outputHash = "...";
      ...
    };

  produces.

  This does change the output path for such fixed-output derivations.
  Fortunately they are quite rare.  The most common use is fetchsvn
  calls with SHA-256 hashes.  (There are a handful of those is
  Nixpkgs, mostly unstable development packages.)
  
* Documented the computation of store paths (in store-api.cc).
2008-12-03 15:06:30 +00:00