[dbconnector] protect db information with mutex #423
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STL containers are only thread safe for reads. But not for writes. protect the db information variables with rwlock. Signed-off-by: Ying Xie <[email protected]>
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This change is intended to address issue sonic-net/sonic-buildimage#6103. However, after added this tentative protection, I realized that there is no code removing anything from m_db_info. So I guess this protection won't really protect us against the issue above? |
common/dbconnector.h
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| @@ -54,6 +55,7 @@ class SonicDBConfig | |||
| static bool isGlobalInit() { return m_global_init; }; | |||
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| private: | |||
| static pthread_rwlock_t db_info_lock; | |||
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make this static seems like bad idea to me
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All the information under protection are static variables. That is why this lock is also static.
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yea, entire class is static, which is bad XD
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@yxieca What is main motivation for this change? You are manually locking/unlocking lock in many places and it could be easy to forget to do that when code will grow. At least wrapping that to class and release in destructor. Also is std::shared_lock what you are looking for? also mistake in title "dbconnectgor" |
yxieca
changed the title
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Is issue related to m_inst_info/m_db_info ? those are static map, and in general it's advised to not uses statics, since they "wired" things can happen process is shutdown, depends on complexity, and threads running, it could happen that some destroyed data is still in use which can lead to some really hard to track errors |
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This SonicDBConfig class don't see to me as critical performance class, so std::recursive_mutex would make more sense and more clean solution. Also, i know not the scope of this PR, but i don't see a reason to make this normal non static class, not even a singleton. |
All the Refers to: common/dbconnector.cpp:70 in 74cf24e. [](commit_id = 74cf24e, deletion_comment = False) |
common/dbconnector.cpp
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| @@ -141,11 +142,13 @@ void SonicDBConfig::initializeGlobalConfig(const string &file) | |||
| catch (domain_error& e) | |||
| { | |||
| SWSS_LOG_ERROR("key doesn't exist in json object, NULL value has no iterator >> %s\n", e.what()); | |||
| pthread_rwlock_unlock(&db_info_lock); | |||
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pthread_rwlock_unlock [](start = 12, length = 21)
Better to use std::lock_guard
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Great idea. If we decide to move forward. I'll make change accordingly
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yea, and use recursive_mutex as discussed
common/dbconnector.h
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| @@ -6,6 +6,8 @@ | |||
| #include <unordered_map> | |||
| #include <utility> | |||
| #include <memory> | |||
| #include <pthread.h> | |||
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you dont need probably this include
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yes. I added that earlier. it is no longer needed now.
yxieca
changed the title
STL containers are only thread safe for reads. But not for writes. protect the db information variables with rwlock.
Signed-off-by: Ying Xie [email protected]