/**
 * \file lite/src/mge/algo_cache/redis_cache.cpp
 * MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
 *
 * Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 */

#include "lite_build_config.h"

#if !defined(WIN32) && LITE_BUILD_WITH_MGE && LITE_WITH_CUDA
#include "../../misc.h"
#include "redis_cache.h"

#include <iostream>
#include <vector>

namespace {

/*
** Translation Table as described in RFC1113
*/
static const char cb64[] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/*
** Translation Table to decode:
*https://github.com/dgiardini/imgcalkap/blob/master/base64.c
*/
static const char cd64[] =
        "|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$XYZ[\\]^_`"
        "abcdefghijklmnopq";

/*
** encodeblock
**
** encode 3 8-bit binary bytes as 4 '6-bit' characters
*/
void encodeblock(unsigned char in[3], unsigned char out[4], int len) {
    out[0] = cb64[in[0] >> 2];
    out[1] = cb64[((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4)];
    out[2] = (unsigned char)(len > 1 ? cb64[((in[1] & 0x0f) << 2) |
                                            ((in[2] & 0xc0) >> 6)]
                                     : '=');
    out[3] = (unsigned char)(len > 2 ? cb64[in[2] & 0x3f] : '=');
}

/*
** decodeblock
**
** decode 4 '6-bit' characters into 3 8-bit binary bytes
*/
void decodeblock(unsigned char in[4], unsigned char out[3]) {
    out[0] = (unsigned char)(in[0] << 2 | in[1] >> 4);
    out[1] = (unsigned char)(in[1] << 4 | in[2] >> 2);
    out[2] = (unsigned char)(((in[2] << 6) & 0xc0) | in[3]);
}

/**
 * Encode string to base64 string
 * @param input - source string
 * @param outdata - target base64 string
 * @param linesize - max size of line
 */
void encode(const std::vector<std::uint8_t>& input,
            std::vector<std::uint8_t>& outdata, int linesize = 76) {
    outdata.clear();

    unsigned char in[3], out[4];
    int i, len, blocksout = 0;
    size_t j = 0;

    auto* indata = reinterpret_cast<const unsigned char*>(input.data());
    unsigned int insize = input.size();

    while (j <= insize) {
        len = 0;
        for (i = 0; i < 3; i++) {
            in[i] = (unsigned char)indata[j];
            j++;
            if (j <= insize) {
                len++;
            } else {
                in[i] = 0;
            }
        }
        if (len) {
            encodeblock(in, out, len);
            for (i = 0; i < 4; i++) {
                outdata.push_back(out[i]);
            }
            blocksout++;
        }
        if (blocksout >= (linesize / 4) || (j == insize)) {
            if (blocksout) {
                outdata.push_back('\r');
                outdata.push_back('\n');
            }
            blocksout = 0;
        }
    }
}

/**
 * Decode base64 string ot source
 * @param input - base64 string
 * @param outdata - source string
 */
void decode(const std::vector<std::uint8_t>& input,
            std::vector<std::uint8_t>& outdata) {
    outdata.clear();

    unsigned char in[4], out[3], v;
    int i, len;
    size_t j = 0;

    auto* indata = reinterpret_cast<const unsigned char*>(input.data());
    unsigned int insize = input.size();

    while (j <= insize) {
        for (len = 0, i = 0; i < 4 && (j <= insize); i++) {
            v = 0;
            while ((j <= insize) && v == 0) {
                v = (unsigned char)indata[j++];
                v = (unsigned char)((v < 43 || v > 122) ? 0 : cd64[v - 43]);
                if (v) {
                    v = (unsigned char)((v == '$') ? 0 : v - 61);
                }
            }
            if (j <= insize) {
                len++;
                if (v) {
                    in[i] = (unsigned char)(v - 1);
                }
            } else {
                in[i] = 0;
            }
        }
        if (len) {
            decodeblock(in, out);
            for (i = 0; i < len - 1; i++) {
                outdata.push_back(out[i]);
            }
        }
    }
}

/**
 * Encode binary data to base64 buffer
 * @param input - source data
 * @param outdata - target base64 buffer
 * @param linesize
 */
void encode(const std::string& input, std::string& outdata, int linesize = 76) {
    std::vector<std::uint8_t> out;
    std::vector<std::uint8_t> in(input.begin(), input.end());
    encode(in, out, linesize);
    outdata = std::string(out.begin(), out.end());
}

/**
 * Decode base64 buffer to source binary data
 * @param input - base64 buffer
 * @param outdata - source binary data
 */
void decode(const std::string& input, std::string& outdata) {
    std::vector<std::uint8_t> in(input.begin(), input.end());
    std::vector<std::uint8_t> out;
    decode(in, out);
    outdata = std::string(out.begin(), out.end());
}

}  // namespace

using namespace lite;

RedisCache::RedisCache(std::string redis_ip, size_t port, std::string password)
        : m_ip(redis_ip), m_port(port), m_password(password) {
    m_client.auth(password);
    m_client.connect(
            m_ip, m_port,
            [](const std::string& host, std::size_t port,
               cpp_redis::connect_state status) {
                if (status == cpp_redis::connect_state::dropped) {
                    LITE_LOG("client disconnected from %s.", host.c_str());
                    LITE_LOG("Redis server connect to %s :%zu failed.",
                             host.c_str(), port);
                }
            },
            std::uint32_t(200));
}

mgb::Maybe<mgb::PersistentCache::Blob> RedisCache::get(
        const std::string& category, const mgb::PersistentCache::Blob& key) {
    LITE_LOCK_GUARD(m_mtx);
    if (m_old == nullptr) {
        return mgb::None;
    }
    auto mem_result = m_old->get(category, key);
    if (mem_result.valid())
        return mem_result;

    std::string key_str(static_cast<const char*>(key.ptr), key.size);
    std::string redis_key_str;
    encode(category + '@' + key_str, redis_key_str, 24);
    auto result = m_client.get(redis_key_str);
    m_client.sync_commit<double, std::milli>(std::chrono::milliseconds(100));
    LITE_ASSERT(is_valid());
    auto content = result.get();
    if (content.is_null())
        return mgb::None;
    std::string decode_content;
    decode(content.as_string(), decode_content);
    m_old->put(category, key, {decode_content.data(), decode_content.length()});

    return m_old->get(category, key);
}

void RedisCache::put(const std::string& category, const Blob& key,
                     const mgb::PersistentCache::Blob& value) {
    // ScopedTimer t1(std::string("put") + category);
    LITE_LOCK_GUARD(m_mtx);
    std::string key_str(static_cast<const char*>(key.ptr), key.size);
    std::string redis_key_str;
    encode(category + '@' + key_str, redis_key_str);
    std::string value_str(static_cast<const char*>(value.ptr), value.size);
    std::string redis_value_str;
    encode(value_str, redis_value_str);

    auto result = m_client.set(redis_key_str, redis_value_str);
    if (m_old == nullptr) {
        return;
    }
    m_old->put(category, key, value);
    m_client.sync_commit<double, std::milli>(std::chrono::milliseconds(100));
    LITE_ASSERT(is_valid());
}
#endif

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