https://github.com/yinqiwen/mmdata
A c++ embeddable write-once data structure store.
https://github.com/yinqiwen/mmdata
Last synced: 6 months ago
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A c++ embeddable write-once data structure store.
- Host: GitHub
- URL: https://github.com/yinqiwen/mmdata
- Owner: yinqiwen
- Created: 2017-12-21T06:48:20.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2019-04-17T02:08:31.000Z (over 6 years ago)
- Last Synced: 2025-04-01T15:13:01.931Z (6 months ago)
- Language: C++
- Homepage:
- Size: 124 KB
- Stars: 7
- Watchers: 3
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
mmdata
======
A C++ library to store&read complex data sturctures in files.
## Dependency
[Boost Interprocess](http://www.boost.org/doc/libs/1_63_0/doc/html/interprocess.html)
## Features
- Designed for apps wanting to store many complex data sturctures on locally in shared memory or disk files.
- Very fast, which have similar read/write performance compared to same data structure in memory.
## Example
```cpp
#include
#include "mmdata.hpp"
using namespace mmdata;
struct ValueObject
{
SHMString v0;
int64_t v1;
double v2;
SHMVector::Type v3;
ValueObject(const CharAllocator& alloc = CharAllocator() )
: v0(alloc), v1(0), v2(1.0), v3(alloc)
{
}
};
typedef SHMHashMap::Type RootTable;
static int64_t image_maxsize = 100 * 1024 * 1024;
static std::string image_file = "./test.img";
static void build_data_image()
{
MMFileData mfile(image_file, image_maxsize);
RootTable* table = mfile.LoadRootWriteObject();
CharAllocator& alloc = mfile.GetAllocator();
for (size_t i = 0; i < 12345; i++)
{
SHMString key;
char tmp[100];
sprintf(tmp, "key%d", i);
key.assign(tmp);
ValueObject v(alloc);
sprintf(tmp, "value%d", i);
v.v0.assign(tmp);
v.v1 = i + 100;
v.v2 = i * 1000;
v.v3.push_back(i);
v.v3.push_back(i + 1);
v.v3.push_back(i + 2);
table->insert(RootTable::value_type(key, v));
}
int64_t n = mfile.ShrinkWriteFile();
printf("Build data image file with size:%lld\n", n);
}
static void load_data_image()
{
MMFileData mfile(image_file);
const RootTable* read_table = mfile.LoadRootReadObject();
printf("Total %llu entry in data image.\n", read_table->size());
RootTable::const_iterator found = read_table->find("key100");
if (found != read_table->end())
{
const SHMString& key = found->first;
const ValueObject& value = found->second;
printf("FoundEntry: key:%s v0:%s v1:%lld v3:[%d %d %d]\n", key.c_str(), value.v0.c_str(), value.v1, value.v3[0], value.v3[1],
value.v3[2]);
}
}
int main()
{
build_data_image(); // build a local disk file which store data
load_data_image(); // load data into memory
return 0;
}
```
## Embedding mmdata
Just copy all files in folder `src` into your project.