plugins/prefetch/configs.cc

/*
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

/**
 * @file configs.cc
 * @brief Plugin configuration.
 */

#include <charconv> /* std::from_chars() */
#include <cstring>  /* strlen() */
#include <fstream>  /* std::ifstream */
#include <getopt.h> /* getopt_long() */
#include <sstream>  /* std::istringstream */

#include "configs.h"
#include "tsutil/StringCompare.h"

DbgCtl Bg_dbg_ctl{PLUGIN_NAME};

template <typename ContainerType>
static void
commaSeparateString(ContainerType &c, const String &input)
{
  std::istringstream istr(input);
  String             token;

  while (std::getline(istr, token, ',')) {
    c.insert(c.end(), token);
  }
}

static bool
isTrue(const char *arg)
{
  return (ts::iequals("true", arg) || ts::iequals("1", arg) || ts::iequals("yes", arg));
}

static String
fetchOverflowString(const EvalPolicy policy)
{
  switch (policy) {
  case EvalPolicy::Overflow64:
    return "64";
    break;
  case EvalPolicy::Bignum:
    return "Bignum";
    break;
  default:
    return "32";
    break;
  }
}

bool
PrefetchConfig::setFetchOverflow(const char *optarg)
{
  if (nullptr == optarg) {
    return false;
  }
  if (StringView("32") == optarg) {
    _fetchOverflow = EvalPolicy::Overflow32;
  } else if (StringView("64") == optarg) {
    _fetchOverflow = EvalPolicy::Overflow64;
  } else if (ts::iequals("bignum", optarg)) {
    _fetchOverflow = EvalPolicy::Bignum;
  } else {
    return false;
  }
  return true;
}

/**
 * @brief Parses @a optarg as an unsigned integer option value.
 * @param optarg the option value to parse.
 * @param value set to the parsed value on success, untouched on failure.
 * @return true if @a optarg is a non-empty string of decimal digits that fits in @a value.
 */
static bool
parseUnsignedInt(const char *optarg, unsigned &value)
{
  if (nullptr == optarg) {
    return false;
  }

  const char *const end = optarg + strlen(optarg);
  auto const [parsed, ec]{std::from_chars(optarg, end, value)};

  /* from_chars() reports a leading sign or a non-digit as invalid_argument and a value too large
   * for @a value as result_out_of_range. Requiring it to consume the whole string rejects trailing
   * characters such as "10abc". */
  return std::errc{} == ec && parsed == end;
}

/**
 * @brief initializes plugin configuration.
 * @param argc number of plugin parameters
 * @param argv plugin parameters
 */
bool
PrefetchConfig::init(int argc, char *argv[])
{
  static const struct option longopt[] = {
    {const_cast<char *>("front"),              optional_argument, nullptr, 'f'},
    {const_cast<char *>("api-header"),         optional_argument, nullptr, 'h'},
    {const_cast<char *>("cmcd-nor"),           optional_argument, nullptr, 'd'},
    {const_cast<char *>("next-header"),        optional_argument, nullptr, 'n'},
    {const_cast<char *>("fetch-policy"),       optional_argument, nullptr, 'p'},
    {const_cast<char *>("fetch-count"),        optional_argument, nullptr, 'c'},
    {const_cast<char *>("fetch-path-pattern"), optional_argument, nullptr, 'e'},
    {const_cast<char *>("fetch-query"),        optional_argument, nullptr, 'q'},
    {const_cast<char *>("fetch-max"),          optional_argument, nullptr, 'x'},
    {const_cast<char *>("replace-host"),       optional_argument, nullptr, 'r'},
    {const_cast<char *>("name-space"),         optional_argument, nullptr, 's'},
    {const_cast<char *>("metrics-prefix"),     optional_argument, nullptr, 'm'},
    {const_cast<char *>("exact-match"),        optional_argument, nullptr, 'y'},
    {const_cast<char *>("log-name"),           optional_argument, nullptr, 'l'},
    {const_cast<char *>("fetch-overflow"),     optional_argument, nullptr, 'o'},
    {nullptr,                                  0,                 nullptr, 0  },
  };

  bool status = true;
  optind      = 0;

  /* argv contains the "to" and "from" URLs. Skip the first so that the second one poses as the program name. */
  --argc;
  ++argv;

  for (;;) {
    int opt;
    opt = getopt_long(argc, (char *const *)argv, "", longopt, nullptr);

    if (opt == -1) {
      break;
    }

    PrefetchDebug("processing %s", argv[optind - 1]);

    switch (opt) {
    case 'f': /* --front */
      _front = ::isTrue(optarg);
      break;

    case 'h': /* --api-header */
      setApiHeader(optarg);
      break;

    case 'd': /* --cmcd-nor */
      _cmcd_nor = ::isTrue(optarg);
      break;

    case 'n': /* --next-header */
      setNextHeader(optarg);
      break;

    case 'p': /* --fetch-policy */
      setFetchPolicy(optarg);
      break;

    case 'c': /* --fetch-count */
      if (unsigned count = 0; parseUnsignedInt(optarg, count)) {
        setFetchCount(count);
      } else {
        PrefetchError("invalid --fetch-count '%s': expected a non-negative integer", optarg ? optarg : "");
        status = false;
      }
      break;

    case 'e': /* --fetch-path-pattern */ {
      auto pattern = std::make_unique<Pattern>();
      if (nullptr != pattern) {
        if (pattern->init(optarg)) {
          _nextPaths.add(std::move(pattern));
        } else {
          /* An unusable fetch-path-pattern is a configuration error; fail instance creation so ATS
           * refuses to load the remap rule rather than silently running with prefetch disabled. */
          PrefetchError("failed to initialize fetch-path-pattern '%s'", optarg ? optarg : "");
          status = false;
        }
      }
    } break;

    case 'q': /* --fetch-query */ {
      setQueryKey(optarg);
    } break;

    case 'x': /* --fetch-max */
      if (unsigned max = 0; parseUnsignedInt(optarg, max)) {
        setFetchMax(max);
      } else {
        PrefetchError("invalid --fetch-max '%s': expected a non-negative integer", optarg ? optarg : "");
        status = false;
      }
      break;

    case 'o': /* --fetch-overflow */
      if (!setFetchOverflow(optarg)) {
        PrefetchError("invalid --fetch-overflow '%s': expected 32, 64, or bignum", optarg ? optarg : "");
        status = false;
      }
      break;

    case 'r': /* --replace-host */
      setReplaceHost(optarg);
      break;

    case 's': /* --name-space */
      setNameSpace(optarg);
      break;

    case 'm': /* --metrics-prefix */
      setMetricsPrefix(optarg);
      break;

    case 'y': /* --exact-match */
      _exactMatch = ::isTrue(optarg);
      break;

    case 'l': /* --log-name */
      setLogName(optarg);
      break;
    }
  }

  status &= finalize();

  return status;
}

/**
 * @brief provides means for post-processing of the plugin parameters to finalize the configuration or to "cache" some of the
 * decisions for later use.
 * @return true if successful, false if failure.
 */
bool
PrefetchConfig::finalize()
{
  PrefetchDebug("front-end: %s", (_front ? "true" : "false"));
  PrefetchDebug("exact match: %s", (_exactMatch ? "true" : "false"));
  PrefetchDebug("query key: %s", _queryKey.c_str());
  PrefetchDebug("cncd-nor: %s", (_front ? "true" : "false"));
  PrefetchDebug("API header name: %s", _apiHeader.c_str());
  PrefetchDebug("next object header name: %s", _nextHeader.c_str());
  PrefetchDebug("fetch policy parameters: %s", _fetchPolicy.c_str());
  PrefetchDebug("fetch count: %d", _fetchCount);
  PrefetchDebug("fetch concurrently max: %d", _fetchMax);
  String fostr = fetchOverflowString(_fetchOverflow);
  PrefetchDebug("fetch overflow: %.*s", (int)fostr.length(), fostr.data());
  PrefetchDebug("replace host name: %s", _replaceHost.c_str());
  PrefetchDebug("name space: %s", _namespace.c_str());
  PrefetchDebug("log name: %s", _logName.c_str());

  return true;
}