web3-proxy/web3_proxy/src/stats/mod.rs

//! Store "stats" in a database for billing and a different database for graphing
//! TODO: move some of these structs/functions into their own file?
pub mod db_queries;
pub mod influxdb_queries;
mod stat_buffer;

pub use stat_buffer::{SpawnedStatBuffer, StatBuffer};

use crate::app::RpcSecretKeyCache;
use crate::frontend::authorization::{Authorization, RequestMetadata};
use crate::frontend::errors::Web3ProxyError;
use crate::rpcs::one::Web3Rpc;
use anyhow::Context;
use axum::headers::Origin;
use chrono::{DateTime, Months, TimeZone, Utc};
use derive_more::From;
use entities::sea_orm_active_enums::TrackingLevel;
use entities::{balance, referee, referrer, rpc_accounting_v2, rpc_key, user, user_tier};
use influxdb2::models::DataPoint;
use log::{trace, warn};
use migration::sea_orm::prelude::Decimal;
use migration::sea_orm::{
    self, ActiveModelTrait, ColumnTrait, DatabaseConnection, EntityTrait, IntoActiveModel,
    QueryFilter,
};
use migration::{Expr, OnConflict};
use num_traits::ToPrimitive;
use parking_lot::Mutex;
use std::cmp::max;
use std::num::NonZeroU64;
use std::sync::atomic::{self, Ordering};
use std::sync::Arc;

use self::stat_buffer::BufferedRpcQueryStats;

#[derive(Debug, PartialEq, Eq)]
pub enum StatType {
    Aggregated,
    Detailed,
}

pub type BackendRequests = Mutex<Vec<Arc<Web3Rpc>>>;

/// TODO: better name? RpcQueryStatBuilder?
#[derive(Clone, Debug)]
pub struct RpcQueryStats {
    pub authorization: Arc<Authorization>,
    pub method: Option<String>,
    pub archive_request: bool,
    pub error_response: bool,
    pub request_bytes: u64,
    /// if backend_requests is 0, there was a cache_hit
    /// no need to track frontend_request on this. a RpcQueryStats always represents one frontend request
    pub backend_rpcs_used: Vec<Arc<Web3Rpc>>,
    pub response_bytes: u64,
    pub response_millis: u64,
    pub response_timestamp: i64,
    /// Credits used signifies how how much money was used up
    pub credits_used: Decimal,
}

#[derive(Clone, Debug, From, Hash, PartialEq, Eq)]
pub struct RpcQueryKey {
    /// unix epoch time
    /// for the time series db, this is (close to) the time that the response was sent
    /// for the account database, this is rounded to the week
    response_timestamp: i64,
    /// true if an archive server was needed to serve the request
    archive_needed: bool,
    /// true if the response was some sort of JSONRPC error
    error_response: bool,
    /// method tracking is opt-in
    method: Option<String>,
    /// origin tracking is opt-in
    origin: Option<Origin>,
    /// None if the public url was used
    rpc_secret_key_id: Option<NonZeroU64>,
}

/// round the unix epoch time to the start of a period
fn round_timestamp(timestamp: i64, period_seconds: i64) -> i64 {
    timestamp / period_seconds * period_seconds
}

impl RpcQueryStats {
    /// rpc keys can opt into multiple levels of tracking.
    /// we always need enough to handle billing, so even the "none" level still has some minimal tracking.
    /// This "accounting_key" is used in the relational database.
    /// anonymous users are also saved in the relational database so that the host can do their own cost accounting.
    fn accounting_key(&self, period_seconds: i64) -> RpcQueryKey {
        let response_timestamp = round_timestamp(self.response_timestamp, period_seconds);

        let rpc_secret_key_id = self.authorization.checks.rpc_secret_key_id;

        let (method, origin) = match self.authorization.checks.tracking_level {
            TrackingLevel::None => {
                // this RPC key requested no tracking. this is the default
                // do not store the method or the origin
                (None, None)
            }
            TrackingLevel::Aggregated => {
                // this RPC key requested tracking aggregated across all methods and origins
                // TODO: think about this more. do we want the origin or not? grouping free cost per site might be useful. i'd rather not collect things if we don't have a planned purpose though
                let method = None;
                let origin = None;

                (method, origin)
            }
            TrackingLevel::Detailed => {
                // detailed tracking keeps track of the method and origin
                // depending on the request, the origin might still be None
                let method = self.method.clone();
                let origin = self.authorization.origin.clone();

                (method, origin)
            }
        };

        // Depending on method, add some arithmetic around calculating credits_used
        // I think balance should not go here, this looks more like a key thingy
        RpcQueryKey {
            response_timestamp,
            archive_needed: self.archive_request,
            error_response: self.error_response,
            method,
            rpc_secret_key_id,
            origin,
        }
    }

    /// all rpc keys are aggregated in the global stats
    /// TODO: should we store "anon" or "registered" as a key just to be able to split graphs?
    fn global_timeseries_key(&self) -> RpcQueryKey {
        // we include the method because that can be helpful for predicting load
        let method = self.method.clone();
        // we don't store origin in the timeseries db. its only used for optional accounting
        let origin = None;
        // everyone gets grouped together
        let rpc_secret_key_id = None;

        RpcQueryKey {
            response_timestamp: self.response_timestamp,
            archive_needed: self.archive_request,
            error_response: self.error_response,
            method,
            rpc_secret_key_id,
            origin,
        }
    }

    /// rpc keys can opt into more detailed tracking
    fn opt_in_timeseries_key(&self) -> Option<RpcQueryKey> {
        // we don't store origin in the timeseries db. its only optionaly used for accounting
        let origin = None;

        // depending on tracking level, we either skip opt-in stats, track without method, or track with method
        let method = match self.authorization.checks.tracking_level {
            TrackingLevel::None => {
                // this RPC key requested no tracking. this is the default.
                return None;
            }
            TrackingLevel::Aggregated => {
                // this RPC key requested tracking aggregated across all methods
                None
            }
            TrackingLevel::Detailed => {
                // detailed tracking keeps track of the method
                self.method.clone()
            }
        };

        let key = RpcQueryKey {
            response_timestamp: self.response_timestamp,
            archive_needed: self.archive_request,
            error_response: self.error_response,
            method,
            rpc_secret_key_id: self.authorization.checks.rpc_secret_key_id,
            origin,
        };

        Some(key)
    }
}

/// A stat that we aggregate and then store in a database.
/// For now there is just one, but I think there might be others later
#[derive(Debug, From)]
pub enum AppStat {
    RpcQuery(RpcQueryStats),
}

// TODO: move to stat_buffer.rs?
impl BufferedRpcQueryStats {
    fn add(&mut self, stat: RpcQueryStats) {
        // a stat always come from just 1 frontend request
        self.frontend_requests += 1;

        // TODO: is this always okay? is it true that each backend rpc will only be queried once per request? i think so
        let num_backend_rpcs_used = stat.backend_rpcs_used.len() as u64;

        if num_backend_rpcs_used == 0 {
            // no backend request. cache hit!
            self.cache_hits += 1;
        } else {
            // backend requests! cache miss!
            self.cache_misses += 1;

            // a single frontend request might have multiple backend requests
            self.backend_requests += num_backend_rpcs_used;
        }

        self.sum_request_bytes += stat.request_bytes;
        self.sum_response_bytes += stat.response_bytes;
        self.sum_response_millis += stat.response_millis;
        self.sum_credits_used += stat.credits_used;

        // Also record the latest balance for this user ..
        self.latest_balance = stat
            .authorization
            .checks
            .balance
            .unwrap_or(Decimal::from(0));
    }

    // TODO: take a db transaction instead so that we can batch?
    async fn save_db(
        self,
        chain_id: u64,
        db_conn: &DatabaseConnection,
        key: RpcQueryKey,
        rpc_secret_key_cache: Option<&RpcSecretKeyCache>,
    ) -> anyhow::Result<()> {
        anyhow::ensure!(
            key.response_timestamp > 0,
            "no response_timestamp! This is a bug! {:?} {:?}",
            key,
            self
        );

        let period_datetime = Utc.timestamp_opt(key.response_timestamp, 0).unwrap();

        // this is a lot of variables
        let accounting_entry = rpc_accounting_v2::ActiveModel {
            id: sea_orm::NotSet,
            rpc_key_id: sea_orm::Set(key.rpc_secret_key_id.map(Into::into)),
            chain_id: sea_orm::Set(chain_id),
            period_datetime: sea_orm::Set(period_datetime),
            archive_needed: sea_orm::Set(key.archive_needed),
            error_response: sea_orm::Set(key.error_response),
            frontend_requests: sea_orm::Set(self.frontend_requests),
            backend_requests: sea_orm::Set(self.backend_requests),
            backend_retries: sea_orm::Set(self.backend_retries),
            no_servers: sea_orm::Set(self.no_servers),
            cache_misses: sea_orm::Set(self.cache_misses),
            cache_hits: sea_orm::Set(self.cache_hits),
            sum_request_bytes: sea_orm::Set(self.sum_request_bytes),
            sum_response_millis: sea_orm::Set(self.sum_response_millis),
            sum_response_bytes: sea_orm::Set(self.sum_response_bytes),
            sum_credits_used: sea_orm::Set(self.sum_credits_used),
        };

        rpc_accounting_v2::Entity::insert(accounting_entry)
            .on_conflict(
                OnConflict::new()
                    .values([
                        (
                            rpc_accounting_v2::Column::FrontendRequests,
                            Expr::col(rpc_accounting_v2::Column::FrontendRequests)
                                .add(self.frontend_requests),
                        ),
                        (
                            rpc_accounting_v2::Column::BackendRequests,
                            Expr::col(rpc_accounting_v2::Column::BackendRequests)
                                .add(self.backend_requests),
                        ),
                        (
                            rpc_accounting_v2::Column::BackendRetries,
                            Expr::col(rpc_accounting_v2::Column::BackendRetries)
                                .add(self.backend_retries),
                        ),
                        (
                            rpc_accounting_v2::Column::NoServers,
                            Expr::col(rpc_accounting_v2::Column::NoServers).add(self.no_servers),
                        ),
                        (
                            rpc_accounting_v2::Column::CacheMisses,
                            Expr::col(rpc_accounting_v2::Column::CacheMisses)
                                .add(self.cache_misses),
                        ),
                        (
                            rpc_accounting_v2::Column::CacheHits,
                            Expr::col(rpc_accounting_v2::Column::CacheHits).add(self.cache_hits),
                        ),
                        (
                            rpc_accounting_v2::Column::SumRequestBytes,
                            Expr::col(rpc_accounting_v2::Column::SumRequestBytes)
                                .add(self.sum_request_bytes),
                        ),
                        (
                            rpc_accounting_v2::Column::SumResponseMillis,
                            Expr::col(rpc_accounting_v2::Column::SumResponseMillis)
                                .add(self.sum_response_millis),
                        ),
                        (
                            rpc_accounting_v2::Column::SumResponseBytes,
                            Expr::col(rpc_accounting_v2::Column::SumResponseBytes)
                                .add(self.sum_response_bytes),
                        ),
                        (
                            rpc_accounting_v2::Column::SumCreditsUsed,
                            Expr::col(rpc_accounting_v2::Column::SumCreditsUsed)
                                .add(self.sum_credits_used),
                        ),
                    ])
                    .to_owned(),
            )
            .exec(db_conn)
            .await?;

        // TODO: Refactor this function a bit more just so it looks and feels nicer
        // TODO: Figure out how to go around unmatching, it shouldn't return an error, but this is disgusting

        // All the referral & balance arithmetic takes place here
        let rpc_secret_key_id: u64 = match key.rpc_secret_key_id {
            Some(x) => x.into(),
            // Return early if the RPC key is not found, because then it is an anonymous user
            None => return Ok(()),
        };

        // (1) Get the user with that RPC key. This is the referee
        let sender_rpc_key = rpc_key::Entity::find()
            .filter(rpc_key::Column::Id.eq(rpc_secret_key_id))
            .one(db_conn)
            .await?;

        // Technicall there should always be a user ... still let's return "Ok(())" for now
        let sender_user_id: u64 = match sender_rpc_key {
            Some(x) => x.user_id,
            // Return early if the User is not found, because then it is an anonymous user
            // Let's also issue a warning because obviously the RPC key should correspond to a user
            None => {
                warn!(
                    "No user was found for the following rpc key: {:?}",
                    rpc_secret_key_id
                );
                return Ok(());
            }
        };

        // (1) Do some general bookkeeping on the user
        let sender_balance = match balance::Entity::find()
            .filter(balance::Column::UserId.eq(sender_user_id))
            .one(db_conn)
            .await?
        {
            Some(x) => x,
            None => {
                warn!("This user id has no balance entry! {:?}", sender_user_id);
                return Ok(());
            }
        };

        let mut active_sender_balance = sender_balance.clone().into_active_model();

        // Still subtract from the user in any case,
        // Modify the balance of the sender completely (in mysql, next to the stats)
        // In any case, add this to "spent"
        // TODO! we need to do the math in mysql (like with `Expr::col` above). if we do the addition here, there is a race condition
        active_sender_balance.used_balance =
            sea_orm::Set(sender_balance.used_balance + self.sum_credits_used);

        // Also update the available balance
        // TODO! this needs to be queried from the database
        let new_available_balance = max(
            sender_balance.available_balance - self.sum_credits_used,
            Decimal::from(0),
        );
        active_sender_balance.available_balance = sea_orm::Set(new_available_balance);

        active_sender_balance.save(db_conn).await?;

        let downgrade_user = match user::Entity::find()
            .filter(user::Column::Id.eq(sender_user_id))
            .one(db_conn)
            .await?
        {
            Some(x) => x,
            None => {
                warn!("No user was found with this sender id!");
                return Ok(());
            }
        };

        let downgrade_user_role = user_tier::Entity::find()
            .filter(user_tier::Column::Id.eq(downgrade_user.user_tier_id))
            .one(db_conn)
            .await?
            .context(format!(
                "The foreign key for the user's user_tier_id was not found! {:?}",
                downgrade_user.user_tier_id
            ))?;

        // Downgrade a user to premium - out of funds if there's less than 10$ in the account, and if the user was premium before
        // TODO: lets let them get under $1
        // TODO: instead of checking for a specific title, downgrade if the downgrade id is set to anything
        if new_available_balance < Decimal::from(10u64) && downgrade_user_role.title == "Premium" {
            // TODO: we could do this outside the balance low block, but I think its fine. or better, update the cache if <$10 and downgrade if <$1
            if let Some(rpc_secret_key_cache) = rpc_secret_key_cache {
                todo!("expire (or probably better to update) the user cache now that the balance is low");
                // actually i think we need to have 2 caches. otherwise users with 2 keys are going to have seperate caches
                // 1. rpc_secret_key_id -> AuthorizationChecks (cuz we don't want to hit the db every time)
                // 2. user_id -> Balance
            }

            // Only downgrade the user in local process memory, not elsewhere

            // let mut active_downgrade_user = downgrade_user.into_active_model();
            // active_downgrade_user.user_tier_id = sea_orm::Set(downgrade_user_role.id);
            // active_downgrade_user.save(db_conn).await?;
        }

        // TODO:

        // Get the referee, and the referrer
        // (2) Look up the code that this user used. This is the referee table
        let referee_object = match referee::Entity::find()
            .filter(referee::Column::UserId.eq(sender_user_id))
            .one(db_conn)
            .await?
        {
            Some(x) => x,
            None => {
                warn!(
                    "No referral code was found for this user: {:?}",
                    sender_user_id
                );
                return Ok(());
            }
        };

        // (3) Look up the matching referrer in the referrer table
        // Referral table -> Get the referee id
        let user_with_that_referral_code = match referrer::Entity::find()
            .filter(referrer::Column::ReferralCode.eq(referee_object.used_referral_code))
            .one(db_conn)
            .await?
        {
            Some(x) => x,
            None => {
                // TODO: warn seems too verbose for this. it should be fine for a user to not have a referall code, right?
                warn!(
                    "No referrer with that referral code was found {:?}",
                    referee_object
                );
                return Ok(());
            }
        };

        // Ok, now we add the credits to both users if applicable...
        // (4 onwards) Add balance to the referrer,

        // (5) Check if referee has used up $100.00 USD in total (Have a config item that says how many credits account to 1$)
        // Get balance for the referrer (optionally make it into an active model ...)
        let sender_balance = match balance::Entity::find()
            .filter(balance::Column::UserId.eq(referee_object.user_id))
            .one(db_conn)
            .await?
        {
            Some(x) => x,
            None => {
                warn!(
                    "This user id has no balance entry! {:?}",
                    referee_object.user_id
                );
                return Ok(());
            }
        };

        // TODO: don't clone on this. use the active_model later
        let mut active_sender_balance = sender_balance.clone().into_active_model();
        let referrer_balance = match balance::Entity::find()
            .filter(balance::Column::UserId.eq(user_with_that_referral_code.user_id))
            .one(db_conn)
            .await?
        {
            Some(x) => x,
            None => {
                warn!(
                    "This user id has no balance entry! {:?}",
                    referee_object.user_id
                );
                return Ok(());
            }
        };

        // I could try to circumvene the clone here, but let's skip that for now
        let mut active_referee = referee_object.clone().into_active_model();

        // (5.1) If not, go to (7). If yes, go to (6)
        // Hardcode this parameter also in config, so it's easier to tune
        if !referee_object.credits_applied_for_referee
            && (sender_balance.used_balance + self.sum_credits_used) >= Decimal::from(100)
        {
            // (6) If the credits have not yet been applied to the referee, apply 10M credits / $100.00 USD worth of credits.
            // Make it into an active model, and add credits
            // TODO! race condition here! we can't set. need to let the db do the math
            active_sender_balance.available_balance =
                sea_orm::Set(sender_balance.available_balance + Decimal::from(100));
            // Also mark referral as "credits_applied_for_referee"
            active_referee.credits_applied_for_referee = sea_orm::Set(true);
        }

        // (7) If the referral-start-date has not been passed, apply 10% of the credits to the referrer.
        let now = Utc::now();
        let valid_until = DateTime::<Utc>::from_utc(referee_object.referral_start_date, Utc)
            .checked_add_months(Months::new(12))
            .unwrap();
        if now <= valid_until {
            let mut active_referrer_balance = referrer_balance.clone().into_active_model();
            // Add 10% referral fees ...
            active_referrer_balance.available_balance = sea_orm::Set(
                referrer_balance.available_balance + self.sum_credits_used / Decimal::from(10),
            );
            // Also record how much the current referrer has "provided" / "gifted" away
            active_referee.credits_applied_for_referrer =
                sea_orm::Set(referee_object.credits_applied_for_referrer + self.sum_credits_used);
            active_referrer_balance.save(db_conn).await?;
        }

        active_sender_balance.save(db_conn).await?;
        active_referee.save(db_conn).await?;

        Ok(())
    }

    async fn build_timeseries_point(
        self,
        measurement: &str,
        chain_id: u64,
        key: RpcQueryKey,
    ) -> anyhow::Result<DataPoint> {
        let mut builder = DataPoint::builder(measurement);

        builder = builder.tag("chain_id", chain_id.to_string());

        if let Some(rpc_secret_key_id) = key.rpc_secret_key_id {
            builder = builder.tag("rpc_secret_key_id", rpc_secret_key_id.to_string());
        }

        if let Some(method) = key.method {
            builder = builder.tag("method", method);
        }

        builder = builder
            .tag("archive_needed", key.archive_needed.to_string())
            .tag("error_response", key.error_response.to_string())
            .field("frontend_requests", self.frontend_requests as i64)
            .field("backend_requests", self.backend_requests as i64)
            .field("no_servers", self.no_servers as i64)
            .field("cache_misses", self.cache_misses as i64)
            .field("cache_hits", self.cache_hits as i64)
            .field("sum_request_bytes", self.sum_request_bytes as i64)
            .field("sum_response_millis", self.sum_response_millis as i64)
            .field("sum_response_bytes", self.sum_response_bytes as i64)
            // TODO: will this be enough of a range
            // I guess Decimal can be a f64
            // TODO: This should prob be a float, i should change the query if we want float-precision for this (which would be important...)
            .field(
                "sum_credits_used",
                self.sum_credits_used
                    .to_f64()
                    .expect("number is really (too) large"),
            )
            .field(
                "balance",
                self.latest_balance
                    .to_f64()
                    .expect("number is really (too) large"),
            );

        // .round() as i64

        builder = builder.timestamp(key.response_timestamp);

        let point = builder.build()?;

        Ok(point)
    }
}

impl TryFrom<RequestMetadata> for RpcQueryStats {
    type Error = Web3ProxyError;

    fn try_from(mut metadata: RequestMetadata) -> Result<Self, Self::Error> {
        let mut authorization = metadata.authorization.take();

        if authorization.is_none() {
            authorization = Some(Arc::new(Authorization::internal(None)?));
        }

        let authorization = authorization.expect("Authorization will always be set");

        let archive_request = metadata.archive_request.load(Ordering::Acquire);

        // TODO: do this without cloning. we can take their vec
        let backend_rpcs_used = metadata.backend_rpcs_used();

        let request_bytes = metadata.request_bytes as u64;
        let response_bytes = metadata.response_bytes.load(Ordering::Acquire);

        let mut error_response = metadata.error_response.load(Ordering::Acquire);
        let mut response_millis = metadata.response_millis.load(atomic::Ordering::Acquire);

        let response_timestamp = match metadata.response_timestamp.load(atomic::Ordering::Acquire) {
            0 => {
                // no response timestamp!
                if !error_response {
                    // force error_response to true
                    // this can happen when a try operator escapes and metadata.add_response() isn't called
                    trace!(
                        "no response known, but no errors logged. investigate. {:?}",
                        metadata
                    );
                    error_response = true;
                }

                if response_millis == 0 {
                    // get something for millis even if it is a bit late
                    response_millis = metadata.start_instant.elapsed().as_millis() as u64
                }

                // no timestamp given. likely handling an error. set it to the current time
                Utc::now().timestamp()
            }
            x => x,
        };

        let method = metadata.method.take();

        let credits_used = Self::compute_cost(
            request_bytes,
            response_bytes,
            backend_rpcs_used.is_empty(),
            method.as_deref(),
        );

        let x = Self {
            authorization,
            archive_request,
            method,
            backend_rpcs_used,
            request_bytes,
            error_response,
            response_bytes,
            response_millis,
            response_timestamp,
            credits_used,
        };

        Ok(x)
    }
}

impl RpcQueryStats {
    /// Compute cost per request
    /// All methods cost the same
    /// The number of bytes are based on input, and output bytes
    pub fn compute_cost(
        request_bytes: u64,
        response_bytes: u64,
        cache_hit: bool,
        method: Option<&str>,
    ) -> Decimal {
        // some methods should be free. there might be cases where method isn't set (though they should be uncommon)
        if let Some(method) = method.as_ref() {
            if ["eth_chainId"].contains(method) {
                return 0.into();
            }
        }

        // TODO: get cost_minimum, cost_free_bytes, cost_per_byte, cache_hit_divisor from config. each chain will be different
        // pays at least $0.000018 / credits per request
        let cost_minimum = Decimal::new(18, 6);

        // 1kb is included on each call
        let cost_free_bytes = 1024;

        // after that, we add cost per bytes, $0.000000006 / credits per byte
        // amazon charges $.09/GB outbound
        // but we also have to cover our RAM and expensive nics on the servers (haproxy/web3-proxy/blockchains)
        let cost_per_byte = Decimal::new(6, 9);

        let total_bytes = request_bytes + response_bytes;

        let total_chargable_bytes = Decimal::from(total_bytes.saturating_sub(cost_free_bytes));

        let mut cost = cost_minimum + cost_per_byte * total_chargable_bytes;

        // cache hits get a 50% discount
        if cache_hit {
            cost /= Decimal::from(2)
        }

        cost
    }
}