leveldb: size restricted range query

1 files changed, 95 insertions, 33 deletions

diff --git a/datastore-leveldb/src/web.cpp b/datastore-leveldb/src/web.cpp
index 4898451..2adf8eb 100644
--- a/datastore-leveldb/src/web.cpp
+++ b/datastore-leveldb/src/web.cpp
@@ -1,8 +1,12 @@
 #include "web.h"
 #include "db.h"
+#include <algorithm>
+#include <vector>
 #include <leveldb/comparator.h>
 #include <iomanip>
 
+static const leveldb::Comparator *cmp = leveldb::BytewiseComparator();
+
 static inline std::string make_key(uint64_t timestamp) {
     std::stringstream key;
     key << "ts-";
@@ -10,9 +14,17 @@ static inline std::string make_key(uint64_t timestamp) {
     return key.str();
 }
 
-void web_handle_api_value(const boost::cmatch &match, struct mg_connection *conn) {
-//    const struct mg_request_info *request_info = mg_get_request_info(conn);
+static inline bool parse_key(leveldb::Slice &&key, uint64_t *value) {
+    if (key.size() != 20+3) 
+        return false;
+    *value = std::stoul(key.data()+3);
+    return true;
+}
 
+
+const boost::regex web_handle_api_value_R(
+    "/api/value/([a-zA-Z0-9]+)/([0-9]+)");
+void web_handle_api_value(const boost::cmatch &match, struct mg_connection *conn) {
     std::string sensor(match[1].str());
     uint64_t timestamp = std::stoul(match[2].str());
     char buf[1024];
@@ -26,14 +38,39 @@ void web_handle_api_value(const boost::cmatch &match, struct mg_connection *conn
         return;
     }
 
-    std::cout << "sensor=" << sensor << " key=" << make_key(timestamp) << std::endl;
     db->Put(leveldb::WriteOptions(), make_key(timestamp), value);
     mg_printf(conn, "HTTP/1.1 200 Value received\r\n\r\n");
 }
 
-void web_handle_api_range(const boost::cmatch &match, struct mg_connection *conn) {
-    static const leveldb::Comparator *cmp = leveldb::BytewiseComparator();
+static inline void print_json_tuple(struct mg_connection *conn,
+        std::ostringstream &outbuf,
+        leveldb::Slice &&key,
+        leveldb::Slice &&value) {
+
+    size_t key_size =  key.size();
+    if (key_size != 20+3) {
+        std::cerr << "invalid key" << std::endl;
+        return;
+    }
+
+    unsigned int offset = 3; // "ts-"
+    // skip zeros in timestamp
+    while (offset < key_size-1 and *(key.data()+offset) == '0')
+        offset++;
+
+    outbuf << '[';
+    outbuf.write(key.data()+offset, key_size-offset);
+    outbuf << ',';
+    outbuf.write(value.data(), value.size());
+    outbuf << ']';
 
+    mg_write(conn, outbuf.str().c_str(), outbuf.tellp());
+}
+
+
+const boost::regex web_handle_api_range_R(
+    "/api/range/([a-zA-Z0-9]+)/([0-9]+)/([0-9]+)");
+void web_handle_api_range(const boost::cmatch &match, struct mg_connection *conn) {
     std::string sensor(match[1].str());
     uint64_t start = std::stoul(match[2].str());
     uint64_t end = std::stoul(match[3].str());
@@ -42,17 +79,16 @@ void web_handle_api_range(const boost::cmatch &match, struct mg_connection *conn
 
     leveldb::DB *db = getDB(sensor);
     if (db == nullptr) {
-        mg_printf(conn, "HTTP/1.1 500 Internal Error\r\n\r\n");
+        mg_printf(conn, "HTTP/1.1 500 Internal Error\r\n"
+                        "\r\n");
         return;
     }
 
     mg_printf(conn,
-            "HTTP/1.1 200 Value received\r\n"
+            "HTTP/1.1 200 OK\r\n"
             "Content-Type: application/json; encoding=UTF-8\r\n"
             "\r\n");
 
-    std::cout << "sensor=" << sensor << " start=" << start << " end=" << end << std::endl;
-
     std::ostringstream out;
     out << "{'sensor':'" << sensor << "', 'error':null, 'data':[";
     mg_write(conn, out.str().c_str(), out.str().size());
@@ -63,33 +99,59 @@ void web_handle_api_range(const boost::cmatch &match, struct mg_connection *conn
     for (it->Seek(key_start); 
             it->Valid() && cmp->Compare(it->key(), key_end) < 0;
             it->Next()) {
-        const char *key = it->key().data();
-        size_t key_size =  it->key().size();
-        if (key_size != 20+3) {
-            std::cerr << "invalid key" << std::endl;
-            return;
-        }
-
-        unsigned int offset = 3; // "ts-"
-        // skip zeros in timestamp
-        while (offset < key_size-1 and *(key+offset) == '0')
-            offset++;
-
-        if (first)
-            first = false;
-        else
-            outbuf << ',';
-
-        outbuf << '[';
-        outbuf.write(key+offset, key_size-offset);
-        outbuf << ',';
-        outbuf.write(it->value().data(), it->value().size());
-        outbuf << ']';
-
-        mg_write(conn, outbuf.str().c_str(), outbuf.tellp());
+        if (first) first = false;
+        else outbuf << ",";
+        print_json_tuple(conn, outbuf, it->key(), it->value());
         outbuf.seekp(0);
     }
     mg_printf(conn, "]}\r\n");
     delete it;
 }
 
+const boost::regex web_handle_api_range_size_R(
+    "/api/range/([a-zA-Z0-9]+)/([0-9]+)/([0-9]+)/([0-9]+)");
+void web_handle_api_range_size(const boost::cmatch &match, struct mg_connection *conn) {
+    std::string sensor(match[1].str());
+    uint64_t start = std::stoul(match[2].str());
+    uint64_t end = std::stoul(match[3].str());
+    uint64_t size = std::stoul(match[4].str());
+
+    leveldb::DB *db = getDB(sensor);
+    if (db == nullptr) {
+        mg_printf(conn, "HTTP/1.1 500 Internal Error\r\n"
+                        "\r\n");
+        return;
+    }
+
+    mg_printf(conn,
+            "HTTP/1.1 200 OK\r\n"
+            "Content-Type: application/json; encoding=UTF-8\r\n"
+            "\r\n");
+
+    uint64_t step = std::max((uint64_t)1, (end-start) / size);
+
+    std::ostringstream out;
+    out << "{'sensor':'" << sensor << "', "
+        << "'error':null, "
+        << "'size':" << size << ", "
+        << "'step':" << step << ", "
+        << "'data':[";
+    mg_write(conn, out.str().c_str(), out.str().size());
+
+    bool first = true;
+    uint64_t actual_size = 0;
+    std::ostringstream outbuf;
+    leveldb::Iterator* it = db->NewIterator(leveldb::ReadOptions());
+    for (uint64_t key = start; key <= end; key += step) {
+        it->Seek(make_key(key));
+
+        if (first) first = false;
+        else outbuf << ",";
+
+        print_json_tuple(conn, outbuf, it->key(), it->value());
+        outbuf.seekp(0);
+        actual_size++;
+    }
+    mg_printf(conn, "], 'actual_size':%ld}\r\n", actual_size);
+    delete it;
+}