panda3d.core.BamCache¶

class BamCache¶

This class maintains a cache of Bam and/or Txo objects generated from model files and texture images (as well as possibly other kinds of loadable objects that can be stored in bam file format).

This class also maintains a persistent index that lists all of the cached objects (see BamCacheIndex). We go through some considerable effort to make sure this index gets saved correctly to disk, even in the presence of multiple different processes writing to the same index, and without relying too heavily on low-level os-provided file locks (which work poorly with C++ iostreams).

Inheritance diagram

__init__() → None¶

property active¶

Getter

Returns true if the BamCache is currently active, false if it is not. “active” means that the cache should be consulted automatically on loads, “not active” means that objects should be loaded directly without consulting the cache.

This represents the global flag. Also see the individual cache_models, cache_textures, cache_compressed_textures flags.

Setter

Changes the state of the active flag. “active” means that the cache should be consulted automatically on loads, “not active” means that objects should be loaded directly without consulting the cache.

This represents the global flag. Also see the individual cache_models, cache_textures, cache_compressed_textures flags.

Return type: bool

property cache_compiled_shaders¶

Getter

Returns whether compiled shader programs will be stored in the cache, as binary .txo files. See setCacheCompiledShaders().

This also returns false if getActive() is false.

Setter

Indicates whether compiled shader programs will be stored in the cache, as binary .sho files. This may not be supported by all shader languages or graphics renderers.

Return type: bool

property cache_compressed_textures¶

Getter

Returns whether compressed texture files will be stored in the cache, as compressed txo files. See setCacheCompressedTextures().

This also returns false if getActive() is false.

Setter

Indicates whether compressed texture files will be stored in the cache, as compressed txo files. The compressed data may either be generated in-CPU, via the squish library, or it may be extracted from the GSG after the texture has been loaded.

This may be set in conjunction with setCacheTextures(), or independently of it. If setCacheTextures() is true and this is false, all textures will be cached in their uncompressed form. If setCacheTextures() is false and this is true, only compressed textures will be cached, and they will be cached in their compressed form. If both are true, all textures will be cached, in their uncompressed or compressed form appropriately.

Return type: bool

property cache_max_kbytes¶

Getter

Returns the maximum size, in kilobytes, which the cache is allowed to grow to. See setCacheMaxKbytes().

Setter

Specifies the maximum size, in kilobytes, which the cache is allowed to grow to. If a newly cached file would exceed this size, an older file is removed from the cache.

Note that in the case of multiple different processes simultaneously operating on the same cache directory, the actual cache size may slightly exceed this value from time to time due to latency in checking between the processes.

Return type: int

property cache_models¶

Getter

Returns whether model files (e.g. egg files and bam files) will be stored in the cache, as bam files.

This also returns false if getActive() is false.

Setter

Indicates whether model files (e.g. egg files and bam files) will be stored in the cache, as bam files.

Return type: bool

property cache_textures¶

Getter

Returns whether texture files (e.g. egg files and bam files) will be stored in the cache, as txo files.

This also returns false if getActive() is false.

Setter

Indicates whether texture files will be stored in the cache, as uncompressed txo files.

Return type: bool

static considerFlushGlobalIndex() → None¶: If there is a global BamCache object, calls considerFlushIndex() on it.

considerFlushIndex() → None¶: Flushes the index if enough time has elapsed since the index was last flushed.

static flushGlobalIndex() → None¶: If there is a global BamCache object, calls flushIndex() on it.

flushIndex() → None¶: Ensures the index is written to disk.

property flush_time¶

Getter: Returns the time in seconds between automatic flushes of the cache index.
Setter: Specifies the time in seconds between automatic flushes of the cache index.

Return type: int

getActive() → bool¶

Returns true if the BamCache is currently active, false if it is not. “active” means that the cache should be consulted automatically on loads, “not active” means that objects should be loaded directly without consulting the cache.

This represents the global flag. Also see the individual cache_models, cache_textures, cache_compressed_textures flags.

getCacheCompiledShaders() → bool¶

Returns whether compiled shader programs will be stored in the cache, as binary .txo files. See setCacheCompiledShaders().

This also returns false if getActive() is false.

getCacheCompressedTextures() → bool¶

Returns whether compressed texture files will be stored in the cache, as compressed txo files. See setCacheCompressedTextures().

This also returns false if getActive() is false.

getCacheMaxKbytes() → int¶: Returns the maximum size, in kilobytes, which the cache is allowed to grow to. See setCacheMaxKbytes().

getCacheModels() → bool¶

Returns whether model files (e.g. egg files and bam files) will be stored in the cache, as bam files.

This also returns false if getActive() is false.

getCacheTextures() → bool¶

Returns whether texture files (e.g. egg files and bam files) will be stored in the cache, as txo files.

This also returns false if getActive() is false.

getFlushTime() → int¶: Returns the time in seconds between automatic flushes of the cache index.

static getGlobalPtr() → BamCache¶

Returns a pointer to the global BamCache object, which is used automatically by the ModelPool and TexturePool.

Return type: BamCache

getReadOnly() → bool¶: Returns true if the cache is in read-only mode. Normally, the cache starts in read-write mode. It can put itself into read-only mode automatically if it discovers that it does not have write access to the cache.

getRoot() → Filename¶

Returns the current root pathname of the cache. See setRoot().

Return type: Filename

listIndex(out: ostream, indent_level: int) → None¶: Writes the contents of the index to standard output.

lookup(source_filename: Filename, cache_extension: str) → BamCacheRecord¶

Looks up a file in the cache.

If the file is cacheable, then regardless of whether the file is found in the cache or not, this returns a BamCacheRecord. On the other hand, if the file cannot be cached, returns NULL.

If record->has_data() returns true, then the file was found in the cache, and you may call record->extract_data() to get the object. If record->has_data() returns false, then the file was not found in the cache or the cache was stale; and you should reload the source file (calling record->add_dependent_file() for each file loaded, including the original source file), and then call record->set_data() to record the resulting loaded object; and finally, you should call store() to write the cached record to disk.

Return type: BamCacheRecord

property read_only¶

Getter: Returns true if the cache is in read-only mode. Normally, the cache starts in read-write mode. It can put itself into read-only mode automatically if it discovers that it does not have write access to the cache.
Setter: Can be used to put the cache in read-only mode, or take it out of read-only mode. Note that if you put it into read-write mode, and it discovers that it does not have write access, it will put itself right back into read-only mode.

Return type: bool

property root¶

Getter

Returns the current root pathname of the cache. See setRoot().

Setter

Changes the current root pathname of the cache. This specifies where the cache files are stored on disk. This should name a directory that is on a disk local to the machine (not on a network-mounted disk), for instance, /tmp/panda-cache or /c/panda-cache.

If the directory does not already exist, it will be created as a result of this call.

Return type: Filename

setActive(flag: bool) → None¶

Changes the state of the active flag. “active” means that the cache should be consulted automatically on loads, “not active” means that objects should be loaded directly without consulting the cache.

This represents the global flag. Also see the individual cache_models, cache_textures, cache_compressed_textures flags.

setCacheCompiledShaders(flag: bool) → None¶: Indicates whether compiled shader programs will be stored in the cache, as binary .sho files. This may not be supported by all shader languages or graphics renderers.

setCacheCompressedTextures(flag: bool) → None¶

Indicates whether compressed texture files will be stored in the cache, as compressed txo files. The compressed data may either be generated in-CPU, via the squish library, or it may be extracted from the GSG after the texture has been loaded.

This may be set in conjunction with setCacheTextures(), or independently of it. If setCacheTextures() is true and this is false, all textures will be cached in their uncompressed form. If setCacheTextures() is false and this is true, only compressed textures will be cached, and they will be cached in their compressed form. If both are true, all textures will be cached, in their uncompressed or compressed form appropriately.

setCacheMaxKbytes(max_kbytes: int) → None¶

Specifies the maximum size, in kilobytes, which the cache is allowed to grow to. If a newly cached file would exceed this size, an older file is removed from the cache.

Note that in the case of multiple different processes simultaneously operating on the same cache directory, the actual cache size may slightly exceed this value from time to time due to latency in checking between the processes.

setCacheModels(flag: bool) → None¶: Indicates whether model files (e.g. egg files and bam files) will be stored in the cache, as bam files.

setCacheTextures(flag: bool) → None¶: Indicates whether texture files will be stored in the cache, as uncompressed txo files.

setFlushTime(flush_time: int) → None¶: Specifies the time in seconds between automatic flushes of the cache index.

setReadOnly(ro: bool) → None¶: Can be used to put the cache in read-only mode, or take it out of read-only mode. Note that if you put it into read-write mode, and it discovers that it does not have write access, it will put itself right back into read-only mode.

setRoot(root: Filename) → None¶

Changes the current root pathname of the cache. This specifies where the cache files are stored on disk. This should name a directory that is on a disk local to the machine (not on a network-mounted disk), for instance, /tmp/panda-cache or /c/panda-cache.

If the directory does not already exist, it will be created as a result of this call.

store(record: BamCacheRecord) → bool¶: Flushes a cache entry to disk. You must have retrieved the cache record via a prior call to lookup(), and then stored the data via record->set_data(). Returns true on success, false on failure.