bes
Updated for version 3.17.0
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#include <BESDapResponseCache.h>
Public Member Functions | |
virtual libdap::DDS * | cache_dataset (libdap::DDS &dds, const std::string &constraint, BESDapResponseBuilder *rb, libdap::ConstraintEvaluator *eval, std::string &cache_token) |
virtual bool | cache_too_big (unsigned long long current_size) const |
look at the cache size; is it too large? Look at the cache size and see if it is too big. More... | |
virtual bool | create_and_lock (const string &target, int &fd) |
Create a file in the cache and lock it for write access. If the file does not exist, make it, open it for read-write access and get an exclusive lock on it. The locking operation blocks, although that should never happen. More... | |
virtual void | dump (ostream &strm) const |
dumps information about this object More... | |
virtual void | exclusive_to_shared_lock (int fd) |
Transfer from an exclusive lock to a shared lock. If the file has an exclusive write lock on it, change that to a shared read lock. This is an atomic operation. If the call to fcntl(2) is protected by locking the cache, a dead lock will result given typical use of this class. This method exists to help with the situation where one process has the cache locked and is blocking on a shared read lock for a file that a second process has locked exclusively (for writing). By changing the exclusive lock to a shared lock, the first process can get its shared lock and then release the cache. More... | |
virtual string | get_cache_file_name (const string &src, bool mangle=true) |
virtual unsigned long long | get_cache_size () |
Get the cache size. Read the size information from the cache info file and return it. This methods locks the cache. More... | |
virtual bool | get_read_lock (const string &target, int &fd) |
Get a read-only lock on the file if it exists. More... | |
const string | getCacheDirectory () |
const string | getCacheFilePrefix () |
virtual bool | getExclusiveLock (string file_name, int &ref_fd) |
virtual void | lock_cache_read () |
virtual void | lock_cache_write () |
virtual void | purge_file (const string &file) |
Purge a single file from the cache. More... | |
virtual void | unlock_and_close (const string &target) |
virtual void | unlock_cache () |
virtual void | update_and_purge (const string &new_file) |
Purge files from the cache. More... | |
virtual unsigned long long | update_cache_info (const string &target) |
Update the cache info file to include 'target'. More... | |
Static Public Member Functions | |
static bool | dir_exists (const string &dir) |
static BESDapResponseCache * | get_instance (const string &cache_dir, const string &prefix, unsigned long long size) |
static BESDapResponseCache * | get_instance () |
static string | getCacheDirFromConfig () |
static string | getCachePrefixFromConfig () |
static unsigned long | getCacheSizeFromConfig () |
Static Public Attributes | |
static const string | PATH_KEY = "DAP.ResponseCache.path" |
static const string | PREFIX_KEY = "DAP.ResponseCache.prefix" |
static const string | SIZE_KEY = "DAP.ResponseCache.size" |
Protected Member Functions | |
BESDapResponseCache (const string &cache_dir, const string &prefix, unsigned long long size) | |
Protected constructor that takes as arguments keys to the cache directory, file prefix, and size of the cache to be looked up a configuration file. More... | |
void | initialize (const string &cache_dir, const string &prefix, unsigned long long size) |
Protected Attributes | |
string | d_cache_dir |
unsigned long long | d_max_cache_size_in_bytes |
How many bytes can the cache hold before we have to purge. | |
string | d_prefix |
unsigned long long | d_target_size |
Friends | |
class | ResponseCacheTest |
class | StoredResultTest |
This class is used to cache DAP2 response objects.
Definition at line 44 of file BESDapResponseCache.h.
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inlineprotected |
The keys specified are looked up in the specified keys object. If not found or not set correctly then an exception is thrown. I.E., if the cache directory is empty, the size is zero, or the prefix is empty.
cache_dir_key | key to look up in the keys file to find cache dir |
prefix_key | key to look up in the keys file to find the cache prefix |
size_key | key to look up in the keys file to find the cache size (in MBytes) |
BESSyntaxUserError | if keys not set, cache dir or prefix empty, size is 0, or if cache dir does not exist. |
Definition at line 82 of file BESDapResponseCache.h.
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virtualinherited |
Definition at line 694 of file BESFileLockingCache.cc.
References BESFileLockingCache::d_max_cache_size_in_bytes.
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virtualinherited |
target | The name of the file to make/open/lock |
fd | Value-result param that holds the file descriptor of the opened file |
BESBESInternalErroror | if any error except EEXIST is returned by open(2) or if fcntl(2) returns an error. |
Definition at line 527 of file BESFileLockingCache.cc.
References BESFileLockingCache::lock_cache_write(), and BESFileLockingCache::unlock_cache().
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staticinherited |
Does the directory exist?
dir | The pathname to test. |
Definition at line 929 of file BESFileLockingCache.cc.
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virtualinherited |
Displays the pointer value of this instance along with information about this cache.
strm | C++ i/o stream to dump the information to |
Implements BESObj.
Definition at line 943 of file BESFileLockingCache.cc.
References BESFileLockingCache::d_max_cache_size_in_bytes.
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virtualinherited |
fd | The file descriptor that is exclusively locked and which, on exit, will have a shared lock. |
Definition at line 557 of file BESFileLockingCache.cc.
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virtualinherited |
Definition at line 706 of file BESFileLockingCache.cc.
References BESFileLockingCache::lock_cache_read(), and BESFileLockingCache::unlock_cache().
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static |
Get an instance of the BESDapResponseCache object. This class is a singleton, so the first call to any of three 'get_instance()' methods makes an instance and subsequent calls return a pointer to that instance.
cache_dir_key | Key to use to get the value of the cache directory |
prefix_key | Key for the item/file prefix. Each file added to the cache uses this as a prefix so cached items can be easily identified when /tmp is used for the cache. |
size_key | How big should the cache be, in megabytes |
Definition at line 164 of file BESDapResponseCache.cc.
References BESError::get_message().
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static |
Get the default instance of the BESDapResponseCache object. This will read "TheBESKeys" looking for the values of FUNCTION_CACHE_PATH, FUNCTION_CACHE_PREFIX, an FUNCTION_CACHE_SIZE to initialize the cache.
Definition at line 189 of file BESDapResponseCache.cc.
References BESDapResponseBuilder::get_dataset_name(), BESError::get_message(), and BESDapResponseBuilder::serialize_dap2_data_ddx().
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virtualinherited |
Try to get a read-only lock on the file, blocking until we can get it. If the file does not exist, return false.
src | src file that will be cached eventually |
target | a value-result parameter set to the resulting cached file |
Error | if the attempt to get the (shared) lock failed for any reason other than that the file does/did not exist. |
Definition at line 499 of file BESFileLockingCache.cc.
References BESFileLockingCache::lock_cache_read(), and BESFileLockingCache::unlock_cache().
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virtualinherited |
Get an exclusive read/write lock on an existing file.
file_name | The name of the file. |
ref_fp | if successful, the file descriptor of the file on which we have an exclusive read/write lock. |
Error | is thrown to indicate a number of untoward events. |
Definition at line 200 of file BESFileLockingCache.cc.
References BESUtil::assemblePath(), BESFileLockingCache::d_max_cache_size_in_bytes, and BESFileLockingCache::unlock_cache().
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virtualinherited |
Get a shared lock on the 'cache info' file.
Definition at line 591 of file BESFileLockingCache.cc.
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virtualinherited |
Get an exclusive lock on the 'cache info' file. The 'cache info' file is used to control certain cache actions, ensuring that they are atomic. These include making sure that the create_and_lock() and read_and_lock() operations are atomic as well as the purge and related operations.
Definition at line 579 of file BESFileLockingCache.cc.
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virtualinherited |
Purge a single file from the cache. The file might be old, etc., and need to be removed. Don't use this to shrink the cache when it gets too big, use update_and_purge() instead since that file optimizes accesses to the cache control file for several changes in a row.
file | The name of the file to purge. |
Definition at line 873 of file BESFileLockingCache.cc.
References BESFileLockingCache::get_cache_size(), BESFileLockingCache::getExclusiveLock(), BESFileLockingCache::lock_cache_write(), and BESFileLockingCache::unlock_cache().
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virtualinherited |
Unlock the named file.
This does not do any name mangling; it just closes and unlocks whatever is named (or throws BESBESInternalErroror if the file cannot be closed). If the file was opened more than once, all descriptors are closed. If you need to close a specific descriptor, use the other version of unlock_and_close().
file_name | The name of the file to unlock. |
BESBESInternalErroror |
Definition at line 629 of file BESFileLockingCache.cc.
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virtualinherited |
Unlock the cache info file.
Definition at line 605 of file BESFileLockingCache.cc.
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virtualinherited |
Purge files, oldest to newest, if the current size of the cache exceeds the size of the cache specified in the constructor. This method uses an exclusive lock on the cache for the duration of the purge process.
new_file | The name of a file this process just added to the cache. Using fcntl(2) locking there is no way this process can detect its own lock, so the shared read lock on the new file won't keep this process from deleting it (but will keep other processes from deleting it). |
Definition at line 789 of file BESFileLockingCache.cc.
References BESFileLockingCache::cache_too_big(), BESFileLockingCache::lock_cache_write(), and BESFileLockingCache::unlock_cache().
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virtualinherited |
Add the size of the named file to the total cache size recorded in the cache info file. The cache info file is exclusively locked by this method for its duration. This updates the cache info file and returns the new size.
target | The name of the file |
Definition at line 652 of file BESFileLockingCache.cc.
References BESFileLockingCache::lock_cache_write(), and BESFileLockingCache::unlock_cache().