InfluxDB seems to always include some other metadata in the `Content-Type`
header separated by semicolons like `application/json; charset=utf-8`,
and comparing the whole string with `application/json` will always fail,
resulting in almost always useless warnings without any helpful information
for the user what actually went wrong.
They're just useless, since a `CheckResult` handler is never going to be
called without a check result and a checkable can't exist without a
checkcommand.
On shutdown or HA re-connect ConfigObject#SetAuthority(false) is called which
does ObjectLock(this) and ConfigObject#Pause(). GelfWriter#Pause(), with the
above ObjectLock, calls m_WorkQueue.Join(). But items inside that also doing
ObjectLock(this) cause a deadlock.
as they would be re-connected in Resume() (HA).
Before they were still connected during pause and connected X+1 times
after X split-brains (the same data was written X+1 times).
m_DataBuffer may be modified concurrently while StatsFunc() is called, thus
it's unsafe to call size() on it. As write access to m_DataBuffer is already
synchronized by only modifying it from the single work queue thread, instead of
adding a mutex, this commit adds a new std::atomic_size_t which is additionally
updated when modifying m_DataBuffer and can safely be accessed in StatsFunc().
There is no explicit synchronization of access to m_DataBuffer which is fine if
it is only accessed from the single-threaded work queue. However, Stop() also
called Flush() in another thread, leading to concurrent write access to
m_DataBuffer which can result in a crash due to use after free/double free.
Changes in this commit:
* Flush() is renamed to FlushWQ() to show that it should only be called from
the work queue. Additionally, it now asserts that it is running on the work
queue.
* Visibility of some data members is changed from protected to private. No
other classes have to access these at the moment. By this change, accidental
concurrent access from derived classes in the future is prevented.
* Stop() now flushes by posting FlushWQ() to the work queue and joining it.
IdoMysqlConnection, IdoPgsqlConnection, IcingaDB, and ElasticsearchWriter
require passwords in their configuration to authenticate against external
services. This commit ensures that these can no longer be accessed using the
API.
Boost.Beast changed the signature of the previously used generic `set`
method so that it no longer accepts integer types, however there is
alreay a more specific method for setting the Content-Length header, so
use this one instead.
