std::random_device() uses the relatively slow /dev/urandom, and we rarely if
ever intend to use it directly - we normally want to use it to seed a faster
random_engine (a pseudo-random number generator).
In many places in the code, we first created a random_device variable, and then
using it created a random_engine variable. However, this practice created the
risk of a programmer accidentally using the random_device object, instead of the
random_engine object, because both have the same API; This hurts performance.
This risk materialized in just two places in the code, utils/uuid.cc and
gms/gossiper.cc. A patch for to uuid.cc was sent previously by Pawel and is
not included in this patch, and the fix for gossiper.{cc,hh} is included here.
To avoid risking the same mistake in the future, this patch switches across the
code to an idiom where the random_device object is not *named*, so cannot be
accidentally used. We use the following idiom:
std::default_random_engine _engine{std::random_device{}()};
Here std::random_device{}() creates the random device (/dev/urandom) and pulls
a random integer from it. It then uses this seed to create the random_engine
(the pseudo-random number generator). The std::random_device{} object is
temporary and unnamed, and cannot be unintentionally used directly.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20180726154958.4405-1-nyh@scylladb.com>
This series contains a couple of fixes to the bookkeeping of the view
build process, which could cause data to be left behind in the system
tables.
* git@github.com:duarten/scylla.git materialized-views/view-build-fixes/v1:
Duarte Nunes (3):
db/system_keyspace: Add function to remove view build status of a
shard
db/view: Don't have shard 0 clear other shard's status on drop
db/view: Restrict writes to the distributed system keyspace to shard 0
This series contains a couple of fixes to the adjusting of clustering
keys in the build_progress_virtual_reader, some of which could
potentially cause heap overflows when querying the legacy system table.
* git@github.com:duarten/scylla.git materialized-views/build-progress-virtual-reader-fixes/v1:
Duarte Nunes (3):
db/view/build_progress_virtual_reader: Use correct schema to adjust ck
db/view/build_progress_virtual_reader: Fix full ck detection
db/view/build_progress_virtual_reader: Also adjust end RT bound
Use abstract_type::to_string() to prettify partition key components.
Manually tested by setting --compaction-large-partition-warning-threshold-mb
to zero and inspecting the output for compound and non-compound partition
keys.
As an optimization, the virtual reader doesn't change the underlying
key if it is not full, and hence doesn't include the extra clustering
key. However, this detection is broken because it checked for 3
clustering columns, instead of 2.
This patch fixes that by obtaining the clustering key size from the
underlying schema instead of hardcoding the size.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
The virtual reader adjusts clustering keys obtained from the
underlying, scylla-specific schema, and potentially sheds the extra
clustering key that's absent from the Cassandra-compatible schema.
This patches ensures we use the correct schema to iterator over the
key.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Writing to the distributed system keyspace should be confined to a
single shard of each host, namely shard 0. We were violating this
constraint by having all shards set the host status to "started". This
could be problematic when the build finishes quickly or there's a
concurrent view drop, such that a write done by shard 0 can have a
smaller timestamp than one done by some other shard.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Shard 0 can clear the in-progress build status of all shards when a
view finishes building, because we are ensured all writes to the
system table have completed with earlier timestamps.
This is not the case when dropping a view. A drop can happen
concurrently with the build, in which case shard 0 may process the
notification before another shard receives it, and before that shard
writes to the system table.
Fix this by ensuring each shard clears its own status on drop.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This patch adds a function that clears the view build in-progress
status for the current shard, similar to the existing one that clears
it across all shards.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
We were considering the token ranges in the size_estimates system
table to be inclusive, which is incorrect and incompatible with
Cassandra.
While we ignore the inclusiveness of the partition_range bounds when
selecting sstables, we do take it into account in
estimated_keys_for_range(). We would thus select the correct sstables,
but could over-estimate the range size nonetheless.
Tests: virtual_reader_test(release)
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180709115919.5106-1-duarte@scylladb.com>
Require a timeout parameter for storage_proxy::mutate_begin() and
all its callers (all the way to thrift and cql modification_statement
and batch_statement).
This should fix spurious debug-mode test failures, where overcommit
and general debug slowness result in the default timeouts being
exceeded. Since the tests use infinite timeouts, they should not
time out any more.
Tests: unit (release), with an extra patch that aborts
when a non-infinite timeout is detected.
Message-Id: <20180707204424.17116-1-avi@scylladb.com>
Rebalance hints segments that need to be sent among all present shards.
Ensure that after rebalancing the difference between the number of segments
of any two shards is not greater than 1.
Try to minimize the amount of "file rename" operations in order to achieve the needed result.
Note: "Resharding" is a particular case of rebalancing.
Tests: dtest: hintedhandoff_additional_test.py:TestHintedHandoff.hintedhandoff_rebalance_test
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
Reserving 10% of space for hints managers makes sense if the device
is shared with other components (like /data or /commitlog).
But, if hints directory is mounted on a dedicated storage, it makes
sense to reserve much more - 90% was chosen as a sane limit.
Whether storage is 'dedicated' or not is based on a simple check
if given hints directory is a mount point.
Fixes#3516
Signed-off-by: Piotr Sarna <sarna@scylladb.com>
Instead of having one static space limit for all directories,
space_watchdog now keeps a per-device limit, shared among
hints managers residing on the same disks.
References #3516
Signed-off-by: Piotr Sarna <sarna@scylladb.com>
In order to make space_watchdog device-aware, device_id field
is added to hints manager. It's an equivalent of stat.st_dev
and it identifies the disk that contains manager's root directory.
Signed-off-by: Piotr Sarna <sarna@scylladb.com>
In order to distinguish which directories reside on which devices,
get_device_id function is added to resource manager.
Signed-off-by: Piotr Sarna <sarna@scylladb.com>
Now that we have the controller, we would like to take min_threshold as
a hint. If there is nothing to compact, we can ignore that and start
compacting less than min_threshold SSTables so that the backlog keeps
reducing.
But there are cases in which we don't want min_threshold to be a hint
and we want to enforce it strictly. For instance, if write amplification
is more of a concern than space amplification.
This patch adds a YAML option that allows the user to tell us that. We will
default to false, meaning min_threshold is not strictly enforced.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Previously max_shard_disk_space_size was unconditionally initialized
with the capacity of hints_directory. But, it's likely that
hints_directory doesn't exist at all if hinted handoff is not enabled,
which results in Scylla failing to boot.
So, max_shard_disk_space_size is now initialized with the capacity
of hints_for_views directory, which is always present.
This commit also moves max_shard_disk_space_size to the .cc file
where it belongs - resource_manager.cc.
Tests: unit (release)
Message-Id: <9f7b86b6452af328c05c5c6c55bfad3382e12445.1528977363.git.sarna@scylladb.com>
When I came across db/legacy_schema_migrator.cc, I had no idea what it
does and though I had obvious guesses (it somehow migrates old schemas,
right?) I didn't know what it really does. So after I figured this out,
I wrote this comment so the next person doesn't need to guess.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20180605120225.25173-1-nyh@scylladb.com>
"
The IndexInfo table tracks the secondary indexes that have already
been populated. Since our secondary index implementation is backed by
materialized views, we can virtualize that table so queries are
actually answered by built_views.
Fixes#3483
"
* 'built-indexes-virtual-reader/v2' of github.com:duarten/scylla:
tests/virtual_reader_test: Add test for built indexes virtual reader
db/system_keysace: Add virtual reader for IndexInfo table
db/system_keyspace: Explain that table_name is the keyspace in IndexInfo
index/secondary_index_manager: Expose index_table_name()
db/legacy_schema_migrator: Don't migrate indexes
"
As in #3423, ensuring token order on secondary index queries can be done
by adding an additional column to views that back secondary indexes.
This column is a first clustering column and contains token value,
computed on updates.
This series also updates tests and comments refering to issue 3423.
Tests: unit (release, debug)
"
* 'order_by_token_in_si_5' of https://github.com/psarna/scylla:
cql3: update token order comments
index, tests: add token column to secondary index schema
view: add handling of a token column for secondary indexes
view: add is_index method
In order to ensure token order on secondary index queries,
first clustering column for each view that backs a secondary index
is going to store a token computed from base's partition keys.
After this commit, if there exists a column that is not present
in base schema, it will be filled with computed token.
We would like the clients to be able to route work directly to the right
shards. To do that, they need to know the sharding algorithm and its
parameters.
The algorithm can be copied into the client, but the parameters need to
be exported somewhere. Let's use the local table for that.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
---
v2: force msb to zero on non-murmur
The IndexInfo table tracks the secondary indexes that have already
been populated. Since our secondary index implementation is backed by
materialized views, we can virtualize that table so queries are
actually answered by built_views.
Fixes#3483
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This patch adds the same comment that exists in Apache Cassandra,
explaining that the table_name column in the IndexInfo system table
actually refers to the keyspace name. Don't be fooled.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Now that more than one instance of hints manager can be present
at the same time, registering metrics is moved out of the constructor
to prevent 'registering metrics twice' errors.
Constants related to managing resources are moved to newly created
resource_manager class. Later, this class will be used to manage
(potentially shared) resources of hints managers.
Collections are not going to be fully converted to the IMR just yet and
still use the old serialisation format. This means that they still don't
support fragmented values very well. This patch passes the information
when an atomic_cell is created as a member of a collection so that later
we can avoid fragmenting the value in such cases.
As a prepratation for the switch to the new cell representation this
patch changes the type returned by atomic_cell_view::value() to one that
requires explicit linearisation of the cell value. Even though the value
is still implicitly linearised (and only when managed by the LSA) the
new interface is the same as the target one so that no more changes to
its users will be needed.
Apache Cassandra handles a case where the node hasn't joined the ring
and may consequentially have an outdated view of it. Following the same
reasoning as with the previous patch, we ignore this scenario. It
happens when there are range movements, and this node is bootstrapping,
but there are already other mechanisms in the cluster, such as hinted
handoff and dual-writing to replicas during range movements, that
contribute to this update eventually making its way to the view.
This patch doesn't change any behavior, but it provides the reasoning
why we won't use the batchlog as Cassandra does, or the hinted handoff
log as we will, to later send the update when the node is joined (note
that Cassandra just sends the mutations "later", and doesn't check
again for any condition or change).
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
If no view replica is paired with the current base replica, it means
there's a range movement going on (decommission or move), such that
this base replica is gaining new token ranges. The current node is
thus a pending_endpoint from the POV of the coordinator that sent the
request.
Sending view updates to the view replica this base will eventually be
paired with only makes a difference when the base update didn't make
it to the node which is currently being decommissioned or moved-from.
The update will, however, make it to that node if HH is enabled at the
coordinator, before the range movement finishes, or later to this node
when it becomes a natural endpoint for the token.
We still ensure we send to any pending view endpoints though, at least
until we handle that case more optimally.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
"
This patchset makes all users of query_processor specify their timeouts
explicitly, in preparation for the removal of
cql_statement::execute_internal() (whose main function was to override
timeouts).
"
* tag 'cql-explicit-timeouts/v1' of https://github.com/avikivity/scylla:
query_processor: require clients to specify timeout configuration
query_processor: un-default consistency level in make_internal_options
This commit adapts view_stats structure so it can be passed
to storage_proxy as write stats. Thanks to that, mv replica updates
will not interfere with user write metrics. As a side effect it also
provides more stats to replica view updates.
Closes#3385Closes#3416
This commit adds statistics to row_locker class. Metrics are
independendly counted for all lock types: row<->partition and
exclusive<->shared.
Metrics gathered:
- total acquisitions
- operations that wait on the lock
- histogram of the time spent on waiting on this type of lock
References #3385
References #3416
This commit introduces view statistics:
- updates pushed to local/remote replicas
- updates failed to be pushed to local/remote replicas
Metrics are kept on per-table basis, i.e. updates_pushed_remote
shows the number of total updates (mutations) pushed to all paired
mv replicas that this particular table has.
Every single update is taken into consideration, so if view update
requires removing a row from one view and adding a row to another,
it will be counted as 2 updates.
References #3385
References #3416
Fixes#3446
Previously, only shutdown-synced objects where actually closed,
which is wrong.
This introduces yet another queue, processed together with the
deletion objects, which ensures we explicitly close all objects
that have been discarded.
Message-Id: <20180521140456.32100-1-calle@scylladb.com>
