复现已有算法
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This folder contains a [jsonstore](https://github.com/bluzi/jsonstore)-like storage service. But is multi-threaded and stores everything in memory. Serving as a showcase on how to build a minimally useful RESTful APIs in Drogon.
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## API
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#### /get-token
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Generate a token that the user can use to create, read, modify and delete records.
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* **method**: GET
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* **URL params**: None
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* **Body**: None
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* **Success response**
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* **Code**: 200
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* **Content**: `{"token":"3a322920d42ef0763152a6efff2ed51985530aedd45370f92fd0f0b8dcc30220"}`
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* **Sample call**
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```bash
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❯ curl -XGET http://localhost:8848/get-token
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{"token":"3a322920d42ef0763152a6efff2ed51985530aedd45370f92fd0f0b8dcc30220"}
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```
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#### /{token}
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Create a new JSON object associated with the token
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* **method**: POST
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* **URL params**: None
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* **Body**: The initial JSON object to store
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* **Success response**
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* **Code**: 200
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* **Content**: `{"ok":true}`
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* **Failed response**:
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* **Code**: 500
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* **Why**: Either the token already is associated with the data or request body/content-type is not JSON.
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* **Content**: `{"ok":false}`
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* **Sample call**
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```bash
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❯ curl -XPOST http://localhost:8848/3a322920d42ef0763152a6efff2ed51985530aedd45370f92fd0f0b8dcc30220 \
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-H 'content-type: application/json' -d '{"foo":{"bar":42}}'
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{"ok":true}
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```
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Delete the JSON object associated with the token
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* **method**: DELETE
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* **URL params**: None
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* **Body**: None
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* **Success response**
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* **Code**: 200
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* **Content**: `{"ok":true}`
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* **Sample call**
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```bash
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❯ curl -XDELETE http://localhost:8848/3a322920d42ef0763152a6efff2ed51985530aedd45370f92fd0f0b8dcc30220
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{"ok":true}
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```
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#### /{token}/{some/path/to/data}
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Retrieve data at and below the specified path
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* **method**: GET
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* **URL params**: None
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* **Body**: None
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* **Success response**
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* **Code**: 200
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* **Content**: `{"foo":{"bar":42}}`
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* **Failed response**:
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* **Code**: 500
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* **Why**: No data associated with the provided token, or it does not exist in the JSON object.
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* **Content**: `{"ok":false}`
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* **Sample call**
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```bash
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❯ curl -XGET http://localhost:8848/3a322920d42ef0763152a6efff2ed51985530aedd45370f92fd0f0b8dcc30220/
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{"foo":{"bar":42}}
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```
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Update data at the specified path
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* **method**: PUT
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* **URL params**: None
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* **Body**: The JSON object you wish to replace to
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* **Success response**
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* **Code**: 200
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* **Content**: `{"ok":true}`
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* **Failed response**:
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* **Code**: 500
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* **Why**: No data associated with the provided token or it does not exist in the JSON object.
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* **Content**: `{"ok":false}`
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* **Sample call**
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```bash
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❯ curl -XPUT http://localhost:8848/3a322920d42ef0763152a6efff2ed51985530aedd45370f92fd0f0b8dcc30220/foo \
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-H 'content-type: application/json' -d '{"fruit":"apple"}'
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{"ok":true}
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```
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## Example use
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```bash
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export URL="http://localhost:8848"
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export TOKEN=`curl $URL/get-token -s | sed 's/.*"\([0-9a-f]*\)".*/\1/'`
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printf "Token is: $TOKEN\n"
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printf 'Creating new data \n> '
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curl -XPOST $URL/$TOKEN -H 'content-type: application/json' -d '{"foo":{"bar":42}}'
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printf '\nRetrieving value of data["foo"]["bar"] \n> '
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curl $URL/$TOKEN/foo/bar
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printf '\nModifing data \n> '
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curl -XPUT $URL/$TOKEN/foo -H 'content-type: application/json' -d '{"zoo":"zebra"}'
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printf '\nNow data["foo"]["bar"] no longer exists \n> '
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curl $URL/$TOKEN/foo/bar
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printf '\nDelete data \n> '
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curl -XDELETE $URL/$TOKEN
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echo
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```
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Output:
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```
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Token is: 5e73ba044b45e68b4856925faea268391091f39fc62ab8c58955cf20957018fa
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Creating new data
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> {"ok":true}
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Retrieving value of data["foo"]["bar"]
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> 42
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Modifying data
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> {"ok":true}
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Now data["foo"]["bar"] no longer exists
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> {"ok":false}
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Delete data
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> {"ok":true}
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```
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+214
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#include <drogon/drogon.h>
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using namespace drogon;
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HttpResponsePtr makeFailedResponse()
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{
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Json::Value json;
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json["ok"] = false;
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auto resp = HttpResponse::newHttpJsonResponse(json);
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resp->setStatusCode(k500InternalServerError);
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return resp;
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}
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HttpResponsePtr makeSuccessResponse()
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{
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Json::Value json;
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json["ok"] = true;
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auto resp = HttpResponse::newHttpJsonResponse(json);
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return resp;
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}
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std::string getRandomString(size_t n)
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{
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std::vector<unsigned char> random(n);
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utils::secureRandomBytes(random.data(), random.size());
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// This is cryptographically safe as 256 mod 16 == 0
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static const std::string alphabets = "0123456789abcdef";
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assert(256 % alphabets.size() == 0);
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std::string randomString(n, '\0');
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for (size_t i = 0; i < n; i++)
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randomString[i] = alphabets[random[i] % alphabets.size()];
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return randomString;
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}
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struct DataItem
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{
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Json::Value item;
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std::mutex mtx;
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};
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class JsonStore : public HttpController<JsonStore>
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{
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public:
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METHOD_LIST_BEGIN
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ADD_METHOD_TO(JsonStore::getToken, "/get-token", Get);
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ADD_METHOD_VIA_REGEX(JsonStore::getItem, "/([a-f0-9]{64})/(.*)", Get);
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ADD_METHOD_VIA_REGEX(JsonStore::createItem, "/([a-f0-9]{64})", Post);
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ADD_METHOD_VIA_REGEX(JsonStore::deleteItem, "/([a-f0-9]{64})", Delete);
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ADD_METHOD_VIA_REGEX(JsonStore::updateItem, "/([a-f0-9]{64})/(.*)", Put);
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METHOD_LIST_END
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void getToken(const HttpRequestPtr &,
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std::function<void(const HttpResponsePtr &)> &&callback)
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{
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std::string randomString = getRandomString(64);
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Json::Value res;
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res["token"] = randomString;
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callback(HttpResponse::newHttpJsonResponse(std::move(res)));
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}
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void getItem(const HttpRequestPtr &,
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std::function<void(const HttpResponsePtr &)> &&callback,
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const std::string &token,
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const std::string &path)
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{
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auto itemPtr = [this, &token]() -> std::shared_ptr<DataItem> {
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// It is possible that the item is being removed while another
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// thread tries to look it up. The mutex here prevents that from
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// happening.
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std::lock_guard<std::mutex> lock(storageMtx_);
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auto it = dataStore_.find(token);
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if (it == dataStore_.end())
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return nullptr;
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return it->second;
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}();
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if (itemPtr == nullptr)
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{
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callback(makeFailedResponse());
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return;
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}
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auto &item = *itemPtr;
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// Prevents another thread from writing to the same item while this
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// thread reads. Could cause blockage if multiple clients are asking to
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// read the same object. But that should be rare.
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std::lock_guard<std::mutex> lock(item.mtx);
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Json::Value *valuePtr = walkJson(item.item, path);
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if (valuePtr == nullptr)
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{
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callback(makeFailedResponse());
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return;
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}
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auto resp = HttpResponse::newHttpJsonResponse(*valuePtr);
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callback(resp);
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}
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void updateItem(const HttpRequestPtr &req,
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std::function<void(const HttpResponsePtr &)> &&callback,
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const std::string &token,
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const std::string &path)
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{
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auto jsonPtr = req->jsonObject();
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auto itemPtr = [this, &token]() -> std::shared_ptr<DataItem> {
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// It is possible that the item is being removed while another
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// thread tries to look it up. The mutex here prevents that from
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// happening.
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std::lock_guard<std::mutex> lock(storageMtx_);
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auto it = dataStore_.find(token);
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if (it == dataStore_.end())
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return nullptr;
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return it->second;
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}();
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if (itemPtr == nullptr || jsonPtr == nullptr)
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{
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callback(makeFailedResponse());
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return;
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}
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auto &item = *itemPtr;
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std::lock_guard<std::mutex> lock(item.mtx);
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Json::Value *valuePtr = walkJson(item.item, path, 1);
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if (valuePtr == nullptr)
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{
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callback(makeFailedResponse());
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return;
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}
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std::string key = utils::splitString(path, "/").back();
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(*valuePtr)[key] = *jsonPtr;
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callback(makeSuccessResponse());
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}
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void createItem(const HttpRequestPtr &req,
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std::function<void(const HttpResponsePtr &)> &&callback,
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const std::string &token)
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{
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auto jsonPtr = req->jsonObject();
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if (jsonPtr == nullptr)
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{
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callback(makeFailedResponse());
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return;
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}
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std::lock_guard<std::mutex> lock(storageMtx_);
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if (dataStore_.find(token) == dataStore_.end())
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{
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auto item = std::make_shared<DataItem>();
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item->item = std::move(*jsonPtr);
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dataStore_.insert({token, std::move(item)});
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callback(makeSuccessResponse());
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}
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else
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{
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callback(makeFailedResponse());
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}
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}
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void deleteItem(const HttpRequestPtr &,
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std::function<void(const HttpResponsePtr &)> &&callback,
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const std::string &token)
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{
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std::lock_guard<std::mutex> lock(storageMtx_);
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dataStore_.erase(token);
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callback(makeSuccessResponse());
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}
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protected:
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static Json::Value *walkJson(Json::Value &json,
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const std::string &path,
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size_t ignore_back = 0)
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{
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auto pathElem = utils::splitString(path, "/", false);
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if (pathElem.size() >= ignore_back)
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pathElem.resize(pathElem.size() - ignore_back);
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Json::Value *valuePtr = &json;
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for (const auto &elem : pathElem)
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{
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if (valuePtr->isArray())
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{
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Json::Value &value = (*valuePtr)[std::stoi(elem)];
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if (value.isNull())
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return nullptr;
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valuePtr = &value;
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}
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else
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{
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Json::Value &value = (*valuePtr)[elem];
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if (value.isNull())
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return nullptr;
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valuePtr = &value;
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}
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}
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return valuePtr;
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}
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std::unordered_map<std::string, std::shared_ptr<DataItem>> dataStore_;
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std::mutex storageMtx_;
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};
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int main()
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{
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app().addListener("127.0.0.1", 8848).run();
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}
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