Commit Graph

16026 Commits

Author SHA1 Message Date
Duarte Nunes
8a90e242e4 Merge 'Fix misdetection of remote counter shards' from Paweł
"
The code reading counter cells form sstables verifies that there are no
unsupported local or remote shards. The latter are detected by checking
if all shards are present in the counter cell header (only remote shards
do not have entries there). However, the logic responsible for doing
that was incorrectly computing the total number of counter shards in a
cell if the header was larger than a single counter shard. This resulted
in incorrect complaints that remote shards are present.

Fixes #4206

Tests: unit(release)
"

* tag 'counter-header-fix/v1' of https://github.com/pdziepak/scylla:
  tests/sstables: test counter cell header with large number of shards
  sstables/counters: fix remote counter shard detection

(cherry picked from commit d2d885fb93)
2019-02-11 14:18:54 +02:00
Calle Wilund
8a78c0aba9 commitlog_replayer: Bugfix: finding truncation positions uses local var ref
"uuid" was ref:ed in a continuation. Works 99.9% of the time because
the continuation is not actually delayed (and assuming we begin the
checks with non-truncated (system) cf:s it works).
But if we do delay continuation, the resulting cf map will be
borked.

Fixes #4187.

Message-Id: <20190204141831.3387-1-calle@scylladb.com>
(cherry picked from commit 9cadbaa96f)
2019-02-04 18:02:43 +02:00
Botond Dénes
8a2bbcf138 auth/service: unregister migration listener on stop()
Otherwise any event that triggers notification to this listener would
trigger a heap-use-after-free.

Refs: #4107

Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <b6bbd609371a2312aed7571b05119d59c7d103d7.1548067626.git.bdenes@scylladb.com>
(cherry picked from commit f229dff210)
2019-01-22 17:55:18 +02:00
Pekka Enberg
22c891e6df Update scylla-ami submodule
* dist/ami/files/scylla-ami a425887...fe156a5 (1):
  > scylla_install_ami: update NIC drivers

See scylladb/scylla-ami#44
scylla-2.3.2
2019-01-17 08:45:22 +02:00
Duarte Nunes
1841d0c2d9 tests/gossip_test: Use RAII for orderly destruction
Change the test so that services are correctly teared down, by the
correct order (e.g., storage_service access the messaging_service when
stopping).

Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180814112111.8521-2-duarte@scylladb.com>
(cherry picked from commit 495a92c5b6)
2019-01-08 19:44:58 +02:00
Duarte Nunes
e10107fe5a tests/gossip_test: Don't bind address to avoid conflicts
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180814112111.8521-1-duarte@scylladb.com>
(cherry picked from commit 3956a77235)
2019-01-08 19:44:52 +02:00
Jenkins
0b3a4679db release: prepare for 2.3.2 2019-01-08 14:40:33 +02:00
Avi Kivity
ba60d666a9 Update seastar submodule
* seastar db30251...10ac122 (1):
  > iotune: Initialize io_rates member variables

Fixes #4064.
2019-01-08 11:41:00 +02:00
Avi Kivity
6ea4d0b75c Update seastar submodule
* seastar b846dfe...db30251 (1):
  > reactor: disable nowait aio due to a kernel bug

Fixes #3996.
2018-12-17 15:56:47 +02:00
Vladimir Krivopalov
8c5911f312 database: Capture io_priority_class by reference to avoid dangling ref.
The original reference points to a thread-local storage object that
guaranteed to outlive the continuation, but copying it make the
subsequent calls point to a local object and introduces a use-after-free
bug.

Fixes #3948

Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
(cherry picked from commit 68458148e7)
2018-12-02 13:32:45 +02:00
Tomasz Grabiec
de00d7f5a1 utils: phased_barrier: Make advance_and_await() have strong exception guarantees
Currently, when advance_and_await() fails to allocate the new gate
object, it will throw bad_alloc and leave the phased_barrier object in
an invalid state. Calling advance_and_await() again on it will result
in undefined behavior (typically SIGSEGV) beacuse _gate will be
disengaged.

One place affected by this is table::seal_active_memtable(), which
calls _flush_barrier.advance_and_await(). If this throws, subsequent
flush attempts will SIGSEGV.

This patch rearranges the code so that advance_and_await() has strong
exception guarantees.
Message-Id: <1542645562-20932-1-git-send-email-tgrabiec@scylladb.com>

Fixes #3931.

(cherry picked from commit 57e25fa0f8)
2018-11-21 12:18:08 +02:00
Glauber Costa
e5f9dae4bb remove monitor if sstable write failed
In (almost) all SSTable write paths, we need to inform the monitor that
the write has failed as well. The monitor will remove the SSTable from
controller's tracking at that point.

Except there is one place where we are not doing that: streaming of big
mutations. Streaming of big mutations is an interesting use case, in
which it is done in 2 parts: if the writing of the SSTable fails right
away, then we do the correct thing.

But the SSTables are not commited at that point and the monitors are
still kept around with the SSTables until a later time, when they are
finally committed. Between those two points in time, it is possible that
the streaming code will detect a failure and manually call
fail_streaming_mutations(), which marks the SSTable for deletions. At
that point we should propagate that information to the monitor as well,
but we don't.

Fixes #3732 (hopefully)
Tests: unit (release)

Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <20181114213618.16789-1-glauber@scylladb.com>
(cherry picked from commit 9f403334c8)
2018-11-20 20:40:44 +02:00
Glauber Costa
e13e796290 sstables: correctly parse estimated histograms
In commit a33f0d6, we changed the way we handle arrays during the write
and parse code to avoid reactor stalls. Some potentially big loops were
transformed into futurized loops, and also some calls to vector resizes
were replaced by a reserve + push_back idiom.

The latter broke parsing of the estimated histogram. The reason being
that the vectors that are used here are already initialized internally
by the estimated_histogram object. Therefore, when we push_back, we
don't fill the array all the way from index 0, but end up with a zeroed
beginning and only push back some of the elements we need.

We could revert this array to a resize() call. After all, the reason we
are using reserve + push_back is to avoid calling the constructor member
for each element, but We don't really expect the integer specialization
to do any of that.

However, to avoid confusion with future developers that may feel tempted
to converted this as well for the sake of consistency, it is safer to
just make sure these arrays are zeroed.

Fixes #3918

Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <20181116130853.10473-1-glauber@scylladb.com>
(cherry picked from commit c6811bd877)
2018-11-17 17:20:38 +02:00
Avi Kivity
336c771663 release: prepare for 2.3.1 scylla-2.3.1 2018-10-19 20:53:17 +03:00
Avi Kivity
82968afc25 locator: fix abstract_replication_strategy::get_ranges() and friends violating sort order
get_ranges() is supposed to return ranges in sorted order. However, a35136533d
broke this and returned the range that was supposed to be last in the second
position (e.g. [0, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9]). The broke cleanup, which
relied on the sort order to perform a binary search. Other users of the
get_ranges() family did not rely on the sort order.

Fixes #3872.
Message-Id: <20181019113613.1895-1-avi@scylladb.com>

(cherry picked from commit 1ce52d5432)
2018-10-19 20:52:31 +03:00
Duarte Nunes
383dcffb53 Merge 'Fix issues with endpoint state replication to other shards' from Tomasz
Fixes #3798
Fixes #3694

Tests:

  unit(release), dtest([new] cql_tests.py:TruncateTester.truncate_after_restart_test)

* tag 'fix-gossip-shard-replication-v1' of github.com:tgrabiec/scylla:
  gms/gossiper: Replicate enpoint states in add_saved_endpoint()
  gms/gossiper: Make reset_endpoint_state_map() have effect on all shards
  gms/gossiper: Replicate STATUS change from mark_as_shutdown() to other shards
  gms/gossiper: Always override states from older generations

(cherry picked from commit 48ebe6552c)
2018-10-17 10:09:07 +02:00
Glauber Costa
0c2abc007c api: use longs instead of ints for snapshot sizes
Int types in json will be serialized to int types in C++. They will then
only be able to handle 4GB, and we tend to store more data than that.

Without this patch, listsnapshots is broken in all versions.

Fixes: #3845

Signed-off-by: Glauber Costa <glauber@scylladb.com>
Message-Id: <20181012155902.7573-1-glauber@scylladb.com>
(cherry picked from commit 98332de268)
2018-10-12 22:02:25 +03:00
Avi Kivity
1498c4f150 Update seastar submodule
* seastar ebf4812...b846dfe (1):
  > prometheus: Fix histogram text representation

Fixes #3827.
2018-10-09 16:38:04 +03:00
Eliran Sinvani
f388992a94 cql3 : add workaround to antlr3 null dereference bug
The Antlr3 exception class has a null dereference bug that crashes
the system when trying to extract the exception message using
ANTLR_Exception<...>::displayRecognitionError(...) function. When
a parsing error occurs the CqlParser throws an exception which in
turn processesed for some special cases in scylla to generate a custom
message. The default case however, creates the message using
displayRecognitionError, causing the system to crash.
The fix is a simple workaround, making sure the pointer is not null
before the call to the function. A "proper" fix can't be implemented
because the exception class itself is implemented outside scylla
in antlr headers that resides on the host machine os.

Tested manualy 2 testcases, a typo causing scylla to crash and
a cql comment without a newline at the end also caused scylla to crash.
Ran unit tests (release).

Fixes #3740
Fixes #3764

Signed-off-by: Eliran Sinvani <eliransin@scylladb.com>
Message-Id: <cfc7e0d758d7a855d113bb7c8191b0fd7d2e8921.1538566542.git.eliransin@scylladb.com>
(cherry picked from commit 20f49566a2)
2018-10-04 14:09:41 +03:00
Avi Kivity
310540c11f utils: crc32: mark power crc32 assembly as not requiring an executable stack
The linker uses an opt-in system for non-executable stack: if all object files
opt into a non-executable stack, the binary will have a non-executable stack,
which is very desirable for security. The compiler cooperates by opting into
a non-executable stack whenever possible (always for our code).

However, we also have an assembly file (for fast power crc32 computations).
Since it doesn't opt into a non-executable stack, we get a binary with
executable stack, which Gentoo's build system rightly complains about.

Fix by adding the correct incantation to the file.

Fixes #3799.

Reported-by: Alexys Jacob <ultrabug@gmail.com>
Message-Id: <20181002151251.26383-1-avi@scylladb.com>
(cherry picked from commit aaab8a3f46)
2018-10-02 23:23:23 +03:00
Calle Wilund
7d833023cc storage_proxy: Add missing re-throw in truncate_blocking
Iff truncation times out, we want to log it, but the exception should
not be swallowed, but re-thrown.

Fixes #3796.

Message-Id: <20181001112325.17809-1-calle@scylladb.com>
(cherry picked from commit 2996b8154f)
2018-10-01 21:48:57 +02:00
Avi Kivity
d94ac196e0 Update scylla-ami submodule
* dist/ami/files/scylla-ami e7aa504...a425887 (1):
  > scylla_install_ami: enable ssh_deletekeys

See scylladb/scylla-ami#31
2018-09-30 16:32:40 +03:00
Duarte Nunes
1d7430995e tests/aggregate_fcts_test: Add test case for wrapped types
Provide a test case which checks a type being wrapped in a
reverse_type plays no role in assignment.

Refs #3789

Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180927223201.28152-2-duarte@scylladb.com>
(cherry picked from commit 17578c3579)
2018-09-28 14:34:19 +03:00
Duarte Nunes
b662a7f8a4 cql3/selection/selector: Unwrap types when validating assignment
When validating assignment between two types, it's possible one of
them is wrapped in a reverse_type, if it comes, for example, from the
type associated with a clustering column. When checking for weak
assignment the types are correctly unwrapped, but not when checking
for an exact match, which this patch fixes.

Technically, the receiver is never a reversed_type for the current
callers, but this is the morally correct implementation, as the type
being reversed or not plays no role in assignment.

Tests: unit(release)

Fixes #3789

Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180927223201.28152-1-duarte@scylladb.com>
(cherry picked from commit 5e7bb20c8a)
2018-09-28 14:34:08 +03:00
Paweł Dziepak
447ad72882 transport: fix use-after-free in read_name_and_value_list()
(cherry picked from commit 1eeef4383c)
2018-09-27 14:05:45 +01:00
Duarte Nunes
b8485d3bce cql3/query_processor: Validate presence of statement values timeously
We need to validate before calling query_options::prepare() whether
the set of prepared statement values sent in the query matches the
amount of names we need to bind, otherwise we risk an out-of-bounds
access if the client also specified names together with the values.

Refs #3688

Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180814225607.14215-1-duarte@scylladb.com>
(cherry picked from commit 805ce6e019)
2018-09-27 14:05:37 +01:00
Takuya ASADA
034b0f50db dist/redhat: specify correct repo file path on scylla-housekeeping services
Currently, both scylla-housekeeping-daily/-restart services mistakenly
specify repo file path as "@@REPOFILES@@", witch is copied from .in
template, need to be replace with actual path.

Fixes #3776

Signed-off-by: Takuya ASADA <syuu@scylladb.com>
Message-Id: <20180921031605.9330-1-syuu@scylladb.com>
(cherry picked from commit 21a12aa458)
2018-09-25 12:30:03 +03:00
Avi Kivity
12ec0becf3 messaging: fix unbounded allocation in TLS RPC server
The non-TLS RPC server has an rpc::resource_limits configuration that limits
its memory consumption, but the TLS server does not. That means a many-node
TLS configuration can OOM if all nodes gang up on a single replica.

Fix by passing the limits to the TLS server too.

Fixes #3757.
Message-Id: <20180907192607.19802-1-avi@scylladb.com>

(cherry picked from commit 4553238653)
2018-09-17 20:25:49 +03:00
Piotr Sarna
666b19552d cql3, 2.3: refuse serving multi-restriction indexed queries
Secondary index queries do not work correctly when multiple
restrictions are present - the rest of the restrictions is simply
ignored, which results in too many rows returned to the client.
This 2.3 fix makes these unsafe queries return an error instead.

Refs #3754

Message-Id: <7e470052d8ffc5bd8dc12e0d7f2705f0754afdbb.1536243391.git.sarna@scylladb.com>
2018-09-17 20:16:01 +03:00
Takuya ASADA
178f870a03 dist/ami/files/.scylla_ami_login: fix python error message on unsupported instance type
We changed usage of colorprint() on f8cec2f891,
need to pass format parameters to the function.

Fixes #3680

Signed-off-by: Takuya ASADA <syuu@scylladb.com>
Tested-by: Amos Kong <amos@scylladb.com>
Message-Id: <20180913182450.13308-1-syuu@scylladb.com>
scylla-2.3.0
2018-09-17 14:53:17 +03:00
Pekka Enberg
1b18f16dc1 release: prepare for 2.3.0 2018-09-14 13:52:02 +03:00
Pekka Enberg
28934575e4 docker: Update RPM repository to 2.3 2018-09-12 15:54:17 +02:00
Gleb Natapov
182cbeefb0 mutation_query_test: add test for result size calculation
Check that digest only and digest+data query calculate result size to be
the same.

Message-Id: <20180906153800.GK2326@scylladb.com>
(cherry picked from commit 9e438933a2)
2018-09-12 15:54:17 +02:00
Gleb Natapov
b70fc41a90 mutation_partition: accurately account for result size in digest only queries
When measuring_output_stream is used to calculate result's element size
it incorrectly takes into account not only serialized element size, but
a placeholder that ser::qr_partition__rows/qr_partition__static_row__cells
constructors puts in the beginning. Fix it by taking starting point in a
stream before element serialization and subtracting it afterwords.

Fixes #3755

Message-Id: <20180906153609.GJ2326@scylladb.com>
(cherry picked from commit d7674288a9)
2018-09-12 15:54:12 +02:00
Tomasz Grabiec
debfc795b2 tests: flat_mutation_reader: Use fluent assertions for better error messages
Message-Id: <1531908313-29810-2-git-send-email-tgrabiec@scylladb.com>
(cherry picked from commit dc453d4f5d)
2018-09-12 15:54:09 +02:00
Tomasz Grabiec
0d094575ec tests: flat_mutation_reader_assertions: Introduce produces(mutation_fragment)
Message-Id: <1531908313-29810-1-git-send-email-tgrabiec@scylladb.com>
(cherry picked from commit 604c8baed8)
2018-09-12 15:54:06 +02:00
Tomasz Grabiec
20baef69a9 mutation_fragment: Fix clustering_row::equal() using incorrect column kind
Incorrect column_kind was passed, which may cause wrong type to be
used for comparison if schema contains static columns. Affects only
tests.

Spotted during code review.
Message-Id: <1531144991-2658-1-git-send-email-tgrabiec@scylladb.com>

(cherry picked from commit 1336744a05)
2018-09-07 13:34:26 +02:00
Pekka Enberg
1bac88601d release: prepare for 2.3.rc3 scylla-2.3.rc3 2018-09-07 07:41:46 +03:00
Vlad Zolotarov
e581fd1463 loading_cache: make size() return the size of lru_list instead of loading_shared_values
reloading flow may hold the items in the underlying loading_shared_values
after they have been removed (e.g. via remove(key) API) thereby loading_shared_values.size()
doesn't represent the correct value for the loading_cache. lru_list.size() on the other hand - does.

Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
(cherry picked from commit 1e56c7dd58)
2018-09-06 16:57:22 +03:00
Vlad Zolotarov
b366bff998 loading_cache: make iterator work on top of lru_list iterators instead of loading_shared_values'
Reloading may hold value in the underlying loading_shared_values while
the corresponding cache values have already been deleted.

This may create weird situations like this:

<populate cache with 10 entries>
cache.remove(key1);
for (auto& e : cache) {
    std::out << e << std::endl;
}

<all 10 entries are printed, including the one for "key1">

In order to avoid such situations we are going to make the loading_cache::iterator
to be a transform_iterator of lru_list::iterator instead of loading_shared_values::iterator
because lru_list contains entries only for cached items.

Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
(cherry picked from commit 945d26e4ee)
2018-09-06 16:57:12 +03:00
Gleb Natapov
38e6984ba5 mutation_partition: correctly measure static row size when doing digest calculation
The code uses incorrect output stream in case only digest is requested
and thus getting incorrect data size. Failing to correctly account
for static row size while calculating digest may cause digest mismatch
between digest and data query.

Fixes #3753.

Message-Id: <20180905131219.GD2326@scylladb.com>
(cherry picked from commit 98092353df)
2018-09-06 16:50:58 +03:00
Vlad Zolotarov
332f76579e tests: loading_cache_test: configure a validity timeout in test_loading_cache_loading_different_keys to a greater value
Change the validity timeout from 1s to 1h in order to avoid false alarms
on busy systems: for a short value there is a chance that
(loading_cache.size() == num_loaders) check is going to run after some elements
of the cache have already been evicted.

Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
Message-Id: <20180904193026.7304-1-vladz@scylladb.com>
(cherry picked from commit dae70e1166)
2018-09-06 16:05:42 +03:00
Jesse Haber-Kucharsky
315a03cf6c auth: Use finite time-out for all QUORUM reads
Commit e664f9b0c6 transitioned internal
CQL queries in the auth. sub-system to be executed with finite time-outs
instead of infinite ones.

It should have also modified the functions in `auth/roles-metadata.cc`
to have finite time-outs.

This change fixes some previously failing dtests, particularly around
repair. Without this change, the QUORUM query fails to terminate when
the necessary consistency level cannot be achieved.

Fixes #3736.

Signed-off-by: Jesse Haber-Kucharsky <jhaberku@scylladb.com>
Message-Id: <e244dc3e731b4019f3be72c52a91f23ee4bb68d1.1536163859.git.jhaberku@scylladb.com>
(cherry picked from commit 682805b22c)
2018-09-05 22:54:32 +03:00
Asias He
1847dc7a6a storage_service: Wait for range setup before announcing join status
When a joining node announcing join status through gossip, other
existing nodes will send writes to the joining node. At this time, it
is possible the joining node hasn't learnt the tokens of other nodes
that causes the error like below:

   token_metadata - sorted_tokens is empty in first_token_index!
   storage_proxy - Failed to apply mutation from 127.0.4.1#0:
   std::runtime_error (sorted_tokens is empty in first_token_index!)

To fix, wait for the token range setup before announcing the join
status.

Fixes: #3382
Tests: 60 run of materialized_views_test.py:TestMaterializedViews.add_dc_during_mv_update_test

Message-Id: <01abb21ae3315ae275297e507c5956e5774557ef.1536128531.git.asias@scylladb.com>
(cherry picked from commit 89b769a073)
2018-09-05 15:32:29 +03:00
Eliran Sinvani
dd11b5987e cql3: backport test of multicolumn IN with repetitions.
The test failed after backport of the containing commit (d734d31), the
reason is that the query was missing ALLOW FILTERING which is required.
In newer versions the allow filtering enforcement "misses" some
cases that needs the filtering anotation due to cavaet in testing multi
column restriction for ALLOW FULTERRING requirement. This issue was
introduced as part of refactoring the multicolumn restrictions classes
and already has an open issue: #3574

Tests: Unitests(release)

Signed-off-by: Eliran Sinvani <eliransin@scylladb.com>
Message-Id: <ad88b7218fa55466be7bc4303dc50326a3d59733.1534322238.git.eliransin@scylladb.com>
(cherry picked from commit d734d316a6)
Message-Id: <928f1fbecffa43c4700541ee6603bb4607871510.1536146137.git.eliransin@scylladb.com>
2018-09-05 14:30:07 +03:00
Paweł Dziepak
a134e8699a test.py: do not disable human-readable format with --jenkins flag
When test.py is run with --jenkins flag Boost UTF is asked to generate
an XML file with the test results. This automatically disables the
human-readable output printed to stdout. There is no real reason to do
so and it is actually less confusing when the Boost UTF messages are in
the test output together with Scylla logger messages.

Message-Id: <20180704172913.23462-1-pdziepak@scylladb.com>
(cherry picked from commit 07a429e837)
2018-09-04 14:26:00 +02:00
Takuya ASADA
bd7dcbb8d2 dist/common/scripts/scylla_raid_setup: create scylla-server.service.d when it doesn't exist
When /etc/systemd/system/scylla-server.service.d/capabilities.conf is
not installed, we don't have /etc/systemd/system/scylla-server.service.d/,
need to create it.

Fixes #3738

Signed-off-by: Takuya ASADA <syuu@scylladb.com>
Message-Id: <20180904015841.18433-1-syuu@scylladb.com>
(cherry picked from commit bd8a5664b8)
2018-09-04 14:42:55 +03:00
Tomasz Grabiec
74e61528a6 managed_vector: Make external_memory_usage() ignore reserved space
This ensures that row::external_memory_usage() is invariant to
insertion order of cells.

It should be so, so that accounting of a clustering_row, merged from
multiple MVCC versions by the partition_snapshot_flat_reader on behalf
of a memtable flush, doesn't give a greater result than what is used
by the memtable region. Overaccounting leads to assertion failure in
~flush_memory_accounter.

Fixes #3625 (hopefully).

Message-Id: <1535982513-19922-1-git-send-email-tgrabiec@scylladb.com>
(cherry picked from commit 4fb3f7e8eb)
2018-09-03 19:58:10 +03:00
Duarte Nunes
5eb4fde2d5 Merge 'utils::loading_cache: improve reload() robustness' from Vlad
"This series introduces a few improvements related to a reload flow.

From now on the callback may assume that the "key" parameter value
is kept alive till the end of its execution in the reloading flow.

It may also safely evict as many items from the cache as needed."

Fixes #3606

* 'loading_cache_improve_reload-v1' of https://github.com/vladzcloudius/scylla:
  utils::loading_cache: hold a shared_value_ptr to the value when we reload
  utils::loading_cache::on_timer(): remove not needed capture of "this"
  utils::loading_cache::on_timer(): use chunked_vector for storing elements we want to reload

(cherry picked from commit f6aadd8077)
2018-08-29 10:12:32 +01:00
Duarte Nunes
cc0703f8ca utils/loading_cache: Avoid using invalidated iterators
When periodically reloading the values in the loading_cache, we would
iterate over the list of entries and call the load() function for
those which need to be reloaded.

For some concrete caches, load() can remove the entry from the LRU set,
and can be executed inline from the parallel_for_each(). This means we
could potentially keep iterating using an invalidated iterator.

Fix this by using a temporary container to hold those entries to be
reloaded.

Spotted when reading the code.

Also use if constexpr and fix the comment in the function containing
the changes.

Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180712124143.13638-1-duarte@scylladb.com>
(cherry picked from commit 63b63b0461)
2018-08-29 10:12:11 +01:00