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Merge pull request #312 from BrightID/BrightID-Node-310
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Dynamic TTL
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@siftal
siftal authored Aug 11, 2022
2 parents 77c0a8d + a2fae95 commit 4b903be
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Showing 6 changed files with 224 additions and 92 deletions.
138 changes: 62 additions & 76 deletions web_services/profile/app.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ const NodeCache = require("node-cache");
const config = require("./config");
const { renderStats } = require("./stats");
const bn = require("bignum");
const {TTLExtension, channel_expires_header} = require('./config')

const dataCache = new NodeCache(config.data_cache_config);
const channelCache = new NodeCache(config.channel_config);
Expand All @@ -21,6 +22,19 @@ if (config.is_dev) {
});
}

/* Get remaining time to live of channel in seconds */
const getRemainingTTL = (channelId) => {
// NodeCache.getTtl() actually returns a unix timestamp in ms(!) when channel will expire
const expirationTime = channelCache.getTtl(channelId);
const remainingTTL = expirationTime - Date.now();
return Math.floor(remainingTTL/1000)
}

/* Get expiration timestamp of channel as unix timestamp(seconds since 1970) */
const getExpirationTimestamp = (channelId) => {
return Math.floor(channelCache.getTtl(channelId)/1000)
}

app.get("/", function (req, res, next) {
res.send("BrightID socket server");
});
Expand Down Expand Up @@ -56,7 +70,8 @@ app.post("/upload/:channelId", function (req, res) {
const ttl = requestedTtl || config.defaultTTL;

let channel = channelCache.get(channelId);
if (!channel) {
const channelExisting = !!channel
if (!channelExisting) {
// Create new channel.
channel = {
entries: new Map(),
Expand All @@ -66,57 +81,57 @@ app.post("/upload/:channelId", function (req, res) {
// save channel in cache with requested TTL
channelCache.set(channelId, channel, ttl);
console.log(`Created new channel ${channelId} with TTL ${channel.ttl}`);
} else {
// existing channel. check if this channel was about to expire, but got another upload
if (channel.entries.size === 0) {
console.log(
`Restoring requested TTL ${channel.ttl} for channel ${channelId}`
);
channelCache.ttl(channelId, channel.ttl);
}
}

// Check if there is already data with the provided uuid to prevent duplicates
const existingData = channel.entries.get(uuid);
if (existingData) {
if (existingData === data) {
console.log(
`Received duplicate profile ${uuid} for channel ${channelId}`
);
// Workaround for recovery channels: interpret upload of existing data as request to extend TTL of channel
// TODO: Remove ttl extension when client that knows how to create channels with longer ttl time is released
channelCache.ttl(channelId, channel.ttl);
res.status(201).json({ success: true });
} else {
if (existingData !== data) {
// Same UUID but different content? This is scary. Likely client bug. Bail out.
res
.status(500)
.json({
error: `Profile ${uuid} already exists in channel ${channelId} with different data.`,
});
.status(500)
.json({
error: `Profile ${uuid} already exists in channel ${channelId} with different data.`,
})
return;
}
return;
}

// check channel size
const entrySize = sizeof(data) + sizeof(uuid);
const newSize = channel.size + entrySize;
console.log(
`channel ${channelId} newSize: ${newSize},\t delta: ${entrySize} bytes`
);
if (newSize > config.channel_max_size_bytes) {
// channel full :-(
res
.status(config.channel_limit_response_code)
.json({ error: config.channel_limit_message });
return;
console.log(
`Received duplicate profile ${uuid} for channel ${channelId}`,
)
}

// save data in cache
try {
channel.entries.set(uuid, data);
channel.size = newSize;
if (!existingData) {
// check channel size
const entrySize = sizeof(data) + sizeof(uuid);
const newSize = channel.size + entrySize;
console.log(
`channel ${channelId} newSize: ${newSize},\t delta: ${entrySize} bytes`
);
if (newSize > config.channel_max_size_bytes) {
// channel full :-(
res
.status(config.channel_limit_response_code)
.json({ error: config.channel_limit_message });
return;
}

// save new data
channel.entries.set(uuid, data);
channel.size = newSize;
}

// extend channel TTL if necessary
if (channelExisting) {
const remainingTTL = getRemainingTTL(channelId)
if ( remainingTTL < TTLExtension) {
channelCache.ttl(channelId, TTLExtension)
console.log(`Extending TTL of channel ${channelId}. Old: ${remainingTTL} New: ${getRemainingTTL(channelId)}`)
}
}

res.status(201);
res.append(channel_expires_header, `${getExpirationTimestamp(channelId)}`)
res.json({ success: true });
} catch (e) {
console.log(err);
Expand Down Expand Up @@ -153,6 +168,8 @@ app.get("/download/:channelId/:uuid", function (req, res, next) {
return;
}

res.append(channel_expires_header, `${getExpirationTimestamp(channelId)}`)

res.json({
data: data,
});
Expand Down Expand Up @@ -201,40 +218,11 @@ app.delete("/:channelId/:uuid", function (req, res, next) {

// update channel size
channel.size -= sizeof(data) + sizeof(uuid);

console.log(
`Deleted ${uuid} from channel ${channelId}. New size: ${channel.size}`
);

// handle removing of last entry
if (channel.entries.size === 0) {
// if channel is empty size should also be 0. Double-check.
if (channel.size !== 0) {
console.warn(
`Channel size calculation incorrect. This should not happen.`
);
channel.size = 0;
}

// Reduce remaining TTL. Leave a few minutes TTL in case some upload is
// hanging from a slow connection
const expirationTime = channelCache.getTtl(channelId); // This actually returns a unix timestamp in ms(!) when channel will expire
const remainingTTL = expirationTime - Date.now();
if (remainingTTL > config.finalTTL) {
console.log(
`last element removed from channel ${channelId}. Reducing TTL from ${Math.floor(
remainingTTL / 1000
)} to ${config.finalTTL} secs.`
);
channelCache.ttl(channelId, config.finalTTL);
} else {
console.log(
`last element removed from channel ${channelId}. Remaining TTL: ${remainingTTL}ms.`
);
channelCache.ttl(channelId, config.finalTTL);
}
}

res.append(channel_expires_header, `${getExpirationTimestamp(channelId)}`)
res.status(200);
res.json({ success: true });
});
Expand All @@ -250,11 +238,7 @@ app.get("/list/:channelId", function (req, res, next) {
// get channel
const channel = channelCache.get(channelId);
if (!channel) {
// Don't fail when channel is not existing. Instead return empty array
// res.status(404).json({error: `Channel ${channelId} not found`});
res.json({
profileIds: [],
});
res.status(404).json({error: `channelId ${channelId} not found`})
return;
}

Expand All @@ -265,8 +249,10 @@ app.get("/list/:channelId", function (req, res, next) {
return;
}

res.append(channel_expires_header, `${getExpirationTimestamp(channelId)}`)

res.json({
profileIds: Array.from(channel.entries.keys()), // channel.entries.keys()
profileIds: Array.from(channel.entries.keys()),
});
});

Expand Down
9 changes: 4 additions & 5 deletions web_services/profile/config.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ const port = process.env.BN_WS_PROFILE_SERVICE_PORT || 3000;
const minTTL = 60; // 1 minute
const maxTTL = 60 * 60 * 24; // 24 hours
const defaultTTL = 60 * 15; // 15 minutes
const finalTTL = 600; // 10 minutes grace period to keep empty channels open
const TTLExtension = 600;

/* Cache config for channels */
const channel_config = {
Expand All @@ -29,27 +29,26 @@ const notification_service =
? process.env.NOTIFICATION_SERVICE_DEV
: process.env.NOTIFICATION_SERVICE_RELEASE;

const channel_entry_limit = 30;

const channel_max_size_bytes = is_test
? 1024 // 1 kb when running jest tests
: 1024 * 1024 * 20; // 20 MegaByte normally

const channel_limit_response_code = 440;
const channel_limit_message = "Channel full";
const channel_expires_header = "x-expires";

module.exports = {
is_dev,
port,
channel_config,
data_cache_config,
notification_service,
channel_entry_limit,
channel_max_size_bytes,
channel_limit_response_code,
channel_limit_message,
finalTTL,
channel_expires_header,
minTTL,
maxTTL,
defaultTTL,
TTLExtension,
};
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