initial note
about some SUSv3 Code, need to group C library, C++ library and SUSv3 library individually
/* C library */
#include <errno.h>
/* SUSv3 */
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h> // file control options
#include <sys/time.h>
#include <sys/resource.h>
/* get file metadata */
struct stat sb;
int rv = fstat(fd, &sb); assert(rv == 0);
// TODO:
#include <stdexcept>1'000'000 integer liberature would be allowed in c++14
MAP_POPULATE macro doesn't exist in macOS for mmap()
read in binary: xxd file | more or: hexdump -C file.bin
jump between empty lines, } and { in vim
how to do paralle: only parallel query
#pragma once
// Use placement new. Node *n = new (nodes + i) Node{array[i]};
about binary file: using C library fopen, etc using SUSv3 system call, open, read, write
// way 1: for each attributes, call read once, but system call is expensive
numRead = read(fd, &trainfileID, sizeof(trainfileID));
// way 2, preseve data in char buf[] first and then pass data to data structure
char buf[TFH_SZ];
int numRead = read(fd, buf, TFH_SZ);
// way 3, create a struct, then read and wirte it as a whole
// potencial allignment problem
struct TrainingFileHeader{
char filetype[8]; /* TRAINING */
uint64_t trainingFileID;
uint64_t numPoints;
uint64_t numDims;
};
fd = open(argv[1], O_RDONLY);
read(fd, &tfd2, sizeof(tfd2)); // don't using assert because it checks training file,
// which doesn't necessary come from me
assert(numRead == TFH_SZ);trick format of cstring from: https://stackoverflow.com/questions/15376765/how-to-print-string-first-n-bytes-when-the-strings-length-is-greater-than-n
printf("%.*s", len, str);BoundedPQueue is a good example to use ctor()=delete; As author would wanna disable default constructor.
and explicit key word would be useful to force client use the function as required. No implicit type convertion is allowed.
TODO:
- time measure
- parallel
- writing data
- [ ]
TODO in mail:
- ssh wli100@spiedie.binghamton.edu
- prof from /home/kchiu/packages/linux-x86_64/bin
- std::atomic
- [ ]
- [ ]
ESR, structure padding: http://www.catb.org/esr/structure-packing/
#include <cstdint> // Use stdint.h if using C.
struct TrainingHdr {
char type_string[8];
uint64_t id;
uint64_t n_points;
uint64_t n_dims;
} __attribute__((packed));Define these preprocessor symbols:
-D_GLIBCXX_CONCEPT_CHECKS -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC
In particular, std::vector indexing with [] is now range checked. (Indexing with .at() is always range-checked.)
a good reading about copy elision and std::move: https://source.coveo.com/2018/11/07/interaction-between-move-semantic-and-copy-elision-in-c++/
something about shell history history | tail -50 | grep "something" !numofCommand
this is time to master python Anaconda
from: https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/usr.html /usr is for "User System Resource" not original user
as I would use command line like 4 arguments, it would be nice to have a key map that do move cursor forward a word, delete a word, move to begin(), move to end() TODO: learn ZSH and oh-my-shell
great the correctness is proved
Single UNIX Specification version 3 (SUSv3) portable operating system interface (POSIX)
!! 15.4.2 Permissions on Directory, page.297
macOS doesn't have strace tool