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fb40a72b45
re: Issue https://github.com/Unidata/netcdf-c/issues/2685 re: PR https://github.com/Unidata/netcdf-c/pull/2179 As noted in PR https://github.com/Unidata/netcdf-c/pull/2179, the old code did not allow for reclaiming instances of types, nor for properly copying them. That PR provided new functions capable of reclaiming/copying instances of arbitrary types. However, as noted by Issue https://github.com/Unidata/netcdf-c/issues/2685, using these most general functions resulted in a significant performance degradation, even for common cases. This PR attempts to mitigate the cost of using the general reclaim/copy functions in two ways. First, the previous functions operating at the top level by using ncid and typeid arguments. These functions were augmented with equivalent versions that used the netcdf-c library internal data structures to allow direct access to needed information. These new functions are used internally to the library. The second mitigation involves optimizing the internal functions by providing early tests for common cases. This avoids unnecessary recursive function calls. The overall result is a significant improvement in speed by a factor of roughly twenty -- your mileage may vary. These optimized functions are still not as fast as the original (more limited) functions, but they are getting close. Additional optimizations are possible. But the cost is a significant "uglification" of the code that I deemed a step too far, at least for now. ## Misc. Changes 1. Added a test case to check the proper reclamation/copy of complex types. 2. Found and fixed some places where nc_reclaim/copy should have been used. 3. Replaced, in the netcdf-c library, (almost all) occurrences of nc_reclaim_copy with calls to NC_reclaim/copy. This plus the optimizations is the primary speed-up mechanism. 4. In DAP4, the metadata is held in a substrate in-memory file; this required some changes so that the reclaim/copy code accessed that substrate dispatcher rather than the DAP4 dispatcher. 5. Re-factored and isolated the code that computes if a type is (transitively) variable-sized or not. 6. Clean up the reclamation code in ncgen; adding the use of nc_reclaim exposed some memory problems.
71 lines
2.2 KiB
C
71 lines
2.2 KiB
C
/*********************************************************************
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* Copyright 2018, UCAR/Unidata
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* See netcdf/COPYRIGHT file for copying and redistribution conditions.
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*********************************************************************/
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#ifndef NCOFFSETS_H
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#define NCOFFSETS_H 1
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/* Define indices for every primitive C type */
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/* NAT => NOT-A-TYPE*/
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#define NC_NATINDEX 0
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#define NC_CHARINDEX 1
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#define NC_UCHARINDEX 2
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#define NC_SHORTINDEX 3
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#define NC_USHORTINDEX 4
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#define NC_INTINDEX 5
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#define NC_UINTINDEX 6
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#define NC_LONGINDEX 7
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#define NC_ULONGINDEX 8
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#define NC_LONGLONGINDEX 9
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#define NC_ULONGLONGINDEX 10
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#define NC_FLOATINDEX 11
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#define NC_DOUBLEINDEX 12
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#define NC_PTRINDEX 13
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#define NC_NCVLENINDEX 14
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#define NC_NCTYPES 15
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typedef struct NCalignment {
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char* type_name;
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size_t alignment;
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} NCalignment;
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typedef NCalignment NCtypealignvec;
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/* Capture in struct and in a vector*/
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typedef struct NCtypealignset {
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NCalignment charalign; /* char*/
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NCalignment ucharalign; /* unsigned char*/
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NCalignment shortalign; /* short*/
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NCalignment ushortalign; /* unsigned short*/
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NCalignment intalign; /* int*/
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NCalignment uintalign; /* unsigned int*/
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NCalignment longalign; /* long*/
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NCalignment ulongalign; /* unsigned long*/
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NCalignment longlongalign; /* long long*/
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NCalignment ulonglongalign; /* unsigned long long*/
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NCalignment floatalign; /* float*/
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NCalignment doublealign; /* double*/
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NCalignment ptralign; /* void**/
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NCalignment ncvlenalign; /* nc_vlen_t*/
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} NCtypealignset;
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EXTERNL int NC_class_alignment(int ncclass, size_t*);
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EXTERNL void NC_compute_alignments(void);
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/* From libdispatch/dinstance.c */
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EXTERNL int NC_type_alignment(int ncid, nc_type xtype, size_t*);
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/* From libdispatch/dinstance_intern.c */
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/**
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* Internal version of NC_type_alignment
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*/
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struct NC_FILE_INFO; /* forward */
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struct NC_TYPE_INFO; /* forward */
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EXTERNL int NC_type_alignment_internal(struct NC_FILE_INFO* file, nc_type xtype, struct NC_TYPE_INFO* utype, size_t* alignp);
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EXTERNL uintptr_t NC_read_align(uintptr_t addr, size_t alignment);
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#endif /*NCOFFSETS_H*/
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