terark basic library

Prerequisite

• boost-1.41 or newer
• terark-base use boost as header-only library

Compile

$ cd /path/to/terark-base
$ make

Components

• valvec
• Lexical Cast
• Read text lines

valvec

terark::valvec is a alternative to std::vector, it use malloc/realloc/free to manage memory. Type of terark::valvec<Type> must be memmove-able.

valvec support terark serialization(DataIO).

Fast expansion

valvec is much faster than std::vector when expanding memory, when expanding, std::vector first allocate a larger memory, then copy-cons(move-cons in c++11) old objects, this is slow. But valvec just calling `realloc' to expand the memory, in virtual addressing system, for example:

   void* p = malloc(oldsize); // `p` is a virtual address
   /// do something
   void* q = realloc(p, newsize); // `q` is another virtual address

When available virtual address range pointed by p is not big enough, it is posible to just remap the physical address of p into a larger free virtual address range. Most popular malloc implementations have used remap to get this advantage.

low level functions

• risk_set_data, risk_set_size, risk_set_capacity
• risk_release_ownership

terarkdb use these functions for supporting DFA memory map in an graceful way.

utility functions

   terark::valvec<int> vec;
   vec.push(1); // `push` is an alias of `push_back`
   vec.push(2); // expand when full
   //...
   vec.reserve(vec.size() + 100);
   vec.unchecked_push(123); // assert when full
   int val = vec.pop_val(); // throws when empty
   //...
   while (!vec.empty()) {
      int top = vec.unchecked_pop_val();
      //...
   }

memmove-able

When memmove an object x of type T to another memory block y without destruct x, if y can be used as if it is x, then type T is memmove-able.

For example, gnu std::list,map,set... are not memmove-able, because they have self-references.

Lexical Cast

Both compiling and running are much fast than boost::lexical_cast.

#include <terark/lcast.hpp>

//...
	int    i = terark::lcast("123");
	long   l = terark::lcase(std::string("1") + "23");
	float  f = terark::lcast("1.23");
	double d = terark::lcast("1.23");

Read text lines

#include <terark/util/linebuf.hpp>

//...
	terark::LineBuf line;
	terark::valvec<fstring> fields; // fstring didn't own memory
	while (line.getline(stdin) > 0) {
		line.chomp(); // like perl chomp
		line.split(&fields);
		if (fields.size()) {
			double dval = terark::lcast(fields[0]);
			//...
		}
	}