This used to implicitly never happen due to only discovering each CDB
once.
We may want to carefully support reindexing one day, but we need to do
it carefully (tricky tradeoffs) and it would need further support in
background indexer.
Making this explicit here rather than just turning off rebroadcast in
background index for a few reasons:
- allows *new* files in the same CDB to be indexed
- relying on bugs-at-a-distance cancelling each other out is bound to bite us
- gets us closer to actually supporting reindexing, which requires similar tracking
Differential Revision: https://reviews.llvm.org/D94503
Summary: This will be needed to support call hierarchy
Reviewers: kadircet
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, usaxena95, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D83536
I've dropped the background context parameter, since we in practice just pass the
current context there, and we now have a different way to specify context too.
While here, clean up a couple of comments.
Reviewed By: kadircet
Differential Revision: https://reviews.llvm.org/D83157
Summary:
.clangd/index was well-intentioned in 2754942cba, but `.clangd` is the best
filename for the clangd config file (matching .clang-format and .clang-tidy).
And of course we can't have both .clangd/index and .clangd...
There are a few overlapping goals to satisfy:
- it should be clear from the directory name that this is transient
data that is safe to delete at the cost of recomputation, i.e. a cache
- it should be easy and self-documenting to blacklist these files in .gitignore
- we should have some consistency between filenames in-tree and
corresponding files in user storage (e.g. under XDG's ~/.cache/)
- we should be consistent across platforms (including windows, which
doesn't have distinct cache vs config directories)
So the plan is:
$PROJECT/.clangd (project config)
$PROJECT/.cache/clangd/index/ (project index)
$PROJECT/.cache/clangd/modules/ (maybe in future)
$XDG_CONFIG_HOME/clangd/config.yaml (user config)
$XDG_CACHE_HOME/clangd/index/ (index of non-project files)
$XDG_CACHE_HOME/clangd/modules/ (maybe in future)
This is sensible if XDG_{CONFIG,CACHE}_HOME coincide, and has a simple
.gitignore rule going forward: `.cache/`.
The monorepo gitignore is updated to reflect the backwards-compatible practice:
ignore .clangd/ (with trailing slash) matching index files from clangd 9/10
ignore .cache matching index from clangd 11+, and potentially other tools.
The entries from llvm-project/llvm gitignore are removed (obsolete).
Reviewers: kadircet, hokein
Subscribers: ilya-biryukov, MaskRay, jkorous, omtcyfz, arphaman, usaxena95, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D83099
Summary:
ClangdServer owns the question of exactly which config to create, but
TUScheduler/BackgroundIndex control threads and so decide at which point
to inject it.
Reviewers: kadircet
Subscribers: ilya-biryukov, javed.absar, MaskRay, jkorous, arphaman, usaxena95, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D83095
Summary:
This confusion was inadvertently introduced in a change to the
heavyweight_hardware_concurrency API: 8404aeb56a
- don't indirect through the rebuilder policy when building the thread pool
- document that rebuilder thresholds are exposed for testing only
- don't use 0 as a sentinel value for "all threads", as we use it as a
sentinel value for "synchronous" (though unsupported for BackgroundIndex)
- rather than pick some new sentinel value, just always use 4 threads for tests
Reviewers: kadircet, aganea
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, usaxena95, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D82352
Summary:
Clangd uses FSProvider to get threadsafe views into file systems. This
patch changes naming to make that more explicit.
Depends on D81920
Reviewers: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, usaxena95, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D81998
The goal of this patch is to maximize CPU utilization on multi-socket or high core count systems, so that parallel computations such as LLD/ThinLTO can use all hardware threads in the system. Before this patch, on Windows, a maximum of 64 hardware threads could be used at most, in some cases dispatched only on one CPU socket.
== Background ==
Windows doesn't have a flat cpu_set_t like Linux. Instead, it projects hardware CPUs (or NUMA nodes) to applications through a concept of "processor groups". A "processor" is the smallest unit of execution on a CPU, that is, an hyper-thread if SMT is active; a core otherwise. There's a limit of 32-bit processors on older 32-bit versions of Windows, which later was raised to 64-processors with 64-bit versions of Windows. This limit comes from the affinity mask, which historically is represented by the sizeof(void*). Consequently, the concept of "processor groups" was introduced for dealing with systems with more than 64 hyper-threads.
By default, the Windows OS assigns only one "processor group" to each starting application, in a round-robin manner. If the application wants to use more processors, it needs to programmatically enable it, by assigning threads to other "processor groups". This also means that affinity cannot cross "processor group" boundaries; one can only specify a "preferred" group on start-up, but the application is free to allocate more groups if it wants to.
This creates a peculiar situation, where newer CPUs like the AMD EPYC 7702P (64-cores, 128-hyperthreads) are projected by the OS as two (2) "processor groups". This means that by default, an application can only use half of the cores. This situation could only get worse in the years to come, as dies with more cores will appear on the market.
== The problem ==
The heavyweight_hardware_concurrency() API was introduced so that only *one hardware thread per core* was used. Once that API returns, that original intention is lost, only the number of threads is retained. Consider a situation, on Windows, where the system has 2 CPU sockets, 18 cores each, each core having 2 hyper-threads, for a total of 72 hyper-threads. Both heavyweight_hardware_concurrency() and hardware_concurrency() currently return 36, because on Windows they are simply wrappers over std:🧵:hardware_concurrency() -- which can only return processors from the current "processor group".
== The changes in this patch ==
To solve this situation, we capture (and retain) the initial intention until the point of usage, through a new ThreadPoolStrategy class. The number of threads to use is deferred as late as possible, until the moment where the std::threads are created (ThreadPool in the case of ThinLTO).
When using hardware_concurrency(), setting ThreadCount to 0 now means to use all the possible hardware CPU (SMT) threads. Providing a ThreadCount above to the maximum number of threads will have no effect, the maximum will be used instead.
The heavyweight_hardware_concurrency() is similar to hardware_concurrency(), except that only one thread per hardware *core* will be used.
When LLVM_ENABLE_THREADS is OFF, the threading APIs will always return 1, to ensure any caller loops will be exercised at least once.
Differential Revision: https://reviews.llvm.org/D71775
Summary:
It simply shows the completed/total items on the background queue, e.g.
indexing: 233/1000
The denominator is reset to zero every time the queue goes idle.
The protocol is fairly complicated here (requires creating a remote "progress"
resource before sending updates). We implement the full protocol, but I've added
an extension allowing it to be skipped to reduce the burden on clients - in
particular the lit test takes this shortcut.
The addition of background index progress to DiagnosticConsumer seems ridiculous
at first glance, but I believe that interface is trending in the direction of
"ClangdServer callbacks" anyway. It's due for a rename, but otherwise actually
fits.
Reviewers: kadircet, usaxena95
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, jfb, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D73218
This reverts commit 9c377105da.
[clangd][BackgroundIndexLoader] Directly store DependentTU while loading shard
Summary:
We were deferring the population of DependentTU field in LoadedShard
until BackgroundIndexLoader was consumed. This actually triggers a use after
free since the shards FileToTU was pointing at could've been moved while
consuming the Loader.
Reviewers: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D64980
llvm-svn: 366559
r366458 is causing test failures. r366467 and r366468 had to be reverted as
they were casuing conflict while reverting r366458.
r366468 [clangd] Remove dead code from BackgroundIndex
r366467 [clangd] BackgroundIndex stores shards to the closest project
r366458 [clangd] Refactor background-index shard loading
llvm-svn: 366551
Summary:
Changes persistance logic to store shards at the directory of closest
CDB. Previously we were storing all shards to directory of the CDB that
triggered indexing, it had its downsides.
For example, if you had two TUs coming from a different CDB but depending on the
same header foo.h, we will store the foo.h only for the first CDB, and it would
be missing for the second and we would never persist it since it was actually
present in the memory and persisted before.
This patch still stores only a single copy of a shard, but makes the directory a
function of the file name. So that the shard place will be unique even with
multiple CDBs accessing the file. This directory is determined as the first
directory containing a CDB in the file's parent directories, if no such
directory exists we make use of the home directory.
Reviewers: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D64745
llvm-svn: 366467
Summary:
In practice, opening Foo.h will still often result in Foo.cpp making the
second index build instead of the first, as the rebuild policy doesn't
know to wait.
Reviewers: kadircet
Subscribers: ilya-biryukov, javed.absar, MaskRay, jkorous, arphaman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64575
llvm-svn: 365888
Summary:
Previously it was rebuilding every 5s by default, which was much too frequent
in the long run - the goal was to provide an early build. There were also some
bugs. There were also some bugs, and a dedicated thread was used in production
but not tested.
- rebuilds are triggered by #TUs built, rather than time. This should scale
more sensibly to fast vs slow machines.
- there are two separate indexed-TU thresholds to trigger index build: 5 TUs
for the first build, 100 for subsequent rebuilds.
- rebuild is always done on the regular indexing threads, and is affected by
blockUntilIdle. This means unit/lit tests run the production configuration.
- fixed a bug where we'd rebuild after attempting to load shards, even if there
were no shards.
- the BackgroundIndexTests don't really test the subtleties of the rebuild
policy (for determinism, we call blockUntilIdle, so rebuild-on-idle is enough
to pass the tests). Instead, we expose the rebuilder as a separate class and
have fine-grained tests for it.
Reviewers: kadircet
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64291
llvm-svn: 365531
Summary:
Currently SHA1 is about 10% of our CPU, this patch reduces it to ~1%.
xxhash is a well-defined (stable) non-cryptographic hash optimized for
fast checksums (like crc32).
Collisions shouldn't be a problem, despite the reduced length:
- for actual file content (used to invalidate bg index shards), there
are only two versions that can collide (new shard and old shard).
- for file paths in bg index shard filenames, we would need 2^32 files
with the same filename to expect a collision. Imperfect hashing may
reduce this a bit but it's well beyond what's plausible.
This will invalidate shards on disk (as usual; I bumped the version),
but this time the filenames are changing so the old files will stick
around :-( So this is more expensive than the usual bump, but would be
good to land before the v9 branch when everyone will start using bg index.
Reviewers: kadircet
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64306
llvm-svn: 365311
Summary:
Clangd currently doesn't cache any indexing failures, which results in
retrying those failed files even if their contents haven't changed.
Reviewers: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D63986
llvm-svn: 365120
Summary:
To unify the way we create threads in clangd.
This should simplify landing D50993.
Reviewers: kadircet
Reviewed By: kadircet
Subscribers: MaskRay, jkorous, arphaman, jfb, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D61724
llvm-svn: 360332
Summary: To take up the .clangd folder for other potential uses in the future.
Reviewers: kadircet, sammccall
Reviewed By: kadircet
Subscribers: ioeric, MaskRay, jkorous, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58440
llvm-svn: 354505
Summary:
clangd is using as many threads as logical cores for BackgroundIndex
by default. We observed that it increases latency of foreground tasks.
This patch aims to change that default to number of physical cores to get rid of
that extra latency.
Reviewers: ilya-biryukov
Reviewed By: ilya-biryukov
Subscribers: ioeric, MaskRay, jkorous, arphaman, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D57819
llvm-svn: 353422
Summary:
Some projects make use of clang plugins when building, but clangd is
not aware of those plugins therefore can't work with the same compile command
arguments.
There were multiple places clangd performed commandline manipulations,
this one also moves them all into OverlayCDB.
Reviewers: ilya-biryukov
Subscribers: klimek, sammccall, ioeric, MaskRay, jkorous, arphaman, cfe-commits
Differential Revision: https://reviews.llvm.org/D56841
llvm-svn: 351788
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
Files without any symbols were never marked as updated during indexing, which resulted in failure while writing shards for these files.
This patch fixes the logic to mark files that are seen for the first time but don't contain any symbols as updated.
Reviewers: ilya-biryukov
Reviewed By: ilya-biryukov
Subscribers: ioeric, MaskRay, jkorous, arphaman, cfe-commits
Differential Revision: https://reviews.llvm.org/D56592
llvm-svn: 351170
Summary:
Currently, background index rebuilds symbol index on every indexed file,
which can be inefficient. This patch makes it only rebuild symbol index periodically.
As the rebuild no longer happens too often, we could also build more efficient
dex index.
Reviewers: ilya-biryukov, kadircet
Reviewed By: kadircet
Subscribers: dblaikie, MaskRay, jkorous, arphaman, jfb, cfe-commits
Differential Revision: https://reviews.llvm.org/D55770
llvm-svn: 349496
Summary:
We'll soon have tasks pending for reading shards from disk, we want
them to have normal priority. Because:
- They are not CPU intensive, mostly IO bound.
- Give a good coverage for the project at startup, therefore it is worth
spending some cycles.
- We have only one task per whole CDB rather than one task per file.
Reviewers: ilya-biryukov
Subscribers: ioeric, MaskRay, jkorous, arphaman, jfb, cfe-commits
Differential Revision: https://reviews.llvm.org/D55315
llvm-svn: 349345
Summary:
Currently, there's no way of knowing about header files
using compilation database, since it doesn't contain header files as entries.
Using this information, restoring from cache using compile commands becomes
possible instead of doing directory traversal. Also, we can issue indexing
actions for out-of-date headers even if source files depending on them haven't
changed.
Reviewers: sammccall
Subscribers: ilya-biryukov, ioeric, MaskRay, jkorous, arphaman, cfe-commits
Differential Revision: https://reviews.llvm.org/D54817
llvm-svn: 347669
Summary:
Ownership and configuration:
The auto-index (background index) is maintained by ClangdServer, like Dynamic.
(This means ClangdServer will be able to enqueue preamble indexing in future).
For now it's enabled by a simple boolean flag in ClangdServer::Options, but
we probably want to eventually allow injecting the storage strategy.
New 'sync' command:
In order to meaningfully test the integration (not just unit-test components)
we need a way for tests to ensure the asynchronous index reads/writes occur
before a certain point.
Because these tests and assertions are few, I think exposing an explicit "sync"
command for use in tests is simpler than allowing threading to be completely
disabled in the background index (as we do for TUScheduler).
Bugs:
I fixed a couple of trivial bugs I found while testing, but there's one I can't.
JSONCompilationDatabase::getAllFiles() may return relative paths, and currently
we trigger an assertion that assumes they are absolute.
There's no efficient way to resolve them (you have to retrieve the corresponding
command and then resolve against its directory property). In general I think
this behavior is broken and we should fix it in JSONCompilationDatabase and
require CompilationDatabase::getAllFiles() to be absolute.
Reviewers: kadircet
Subscribers: ilya-biryukov, ioeric, MaskRay, jkorous, arphaman, cfe-commits
Differential Revision: https://reviews.llvm.org/D54894
llvm-svn: 347567
Summary:
Instead of receiving compilation commands, auto-index is triggered by just
filenames to reindex, and gets commands from the global comp DB internally.
This has advantages:
- more of the work can be done asynchronously (fetching compilation commands
upfront can be slow for large CDBs)
- we get access to the CDB which can be used to retrieve interpolated commands
for headers (useful in some cases where the original TU goes away)
- fits nicely with the filename-only change observation from r347297
The interface to GlobalCompilationDatabase gets extended: when retrieving a
compile command, the GCDB can optionally report the project the file belongs to.
This naturally fits together with getCompileCommand: it's hard to implement one
without the other. But because most callers don't care, I've ended up with an
awkward optional-out-param-in-virtual method pattern - maybe there's a better
one.
This is the main missing integration point between ClangdServer and
BackgroundIndex, after this we should be able to add an auto-index flag.
Reviewers: ioeric, kadircet
Subscribers: MaskRay, jkorous, arphaman, cfe-commits, ilya-biryukov
Differential Revision: https://reviews.llvm.org/D54865
llvm-svn: 347538
Summary:
Instead of passing around a list of supported URI schemes in clangd, we
expose an interface to convert a path to URI using any compatible scheme
that has been registered. It favors customized schemes and falls
back to "file" when no other scheme works.
Changes in this patch are:
- URI::create(AbsPath, URISchemes) -> URI::create(AbsPath). The new API finds a
compatible scheme from the registry.
- Remove URISchemes option everywhere (ClangdServer, SymbolCollecter, FileIndex etc).
- Unit tests will use "unittest" by default.
- Move "test" scheme from ClangdLSPServer to ClangdMain.cpp, and only
register the test scheme when lit-test or enable-lit-scheme is set.
(The new flag is added to make lit protocol.test work; I wonder if there
is alternative here.)
Reviewers: sammccall
Reviewed By: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, cfe-commits
Differential Revision: https://reviews.llvm.org/D54800
llvm-svn: 347467
Summary:
This allows us to deduplicate header symbols across TUs. File digests
are collects when collecting symbols/refs. And the index store deduplicates
file symbols based on the file digest.
Reviewers: sammccall, hokein
Reviewed By: sammccall
Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, cfe-commits
Differential Revision: https://reviews.llvm.org/D53433
llvm-svn: 346221
Sam McCall